# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

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# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923 #6

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99957f3
fix: sanitize 502 HTML responses from error messages
Hellnight2005 Feb 4, 2026
1e7ede5
fix: handle UnicodeDecodeError when parsing API responses
Hellnight2005 Feb 4, 2026
8cfe813
fix: guard response.text access to prevent unhandled UnicodeDecodeError
Hellnight2005 Feb 4, 2026
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66 changes: 53 additions & 13 deletions src/lingodotdev/engine.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
"""
try:
return response.json()
except json.JSONDecodeError:
preview = LingoDotDevEngine._truncate_response(response.text)
except (json.JSONDecodeError, UnicodeDecodeError) as err:
try:
text = response.text
except UnicodeDecodeError:
text = response.content.decode("utf-8", errors="replace")

preview = LingoDotDevEngine._truncate_response(text)
raise RuntimeError(
f"Failed to parse API response as JSON (status {response.status_code}). "
f"This may indicate a gateway or proxy error. Response: {preview}"
)
) from err

async def _localize_raw(
self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
response = await self._client.post(url, json=request_data)

if not response.is_success:
response_preview = self._truncate_response(response.text)
if 500 <= response.status_code < 600:
error_details = ""
try:
error_json = response.json()
if isinstance(error_json, dict) and "error" in error_json:
error_details = f" {error_json['error']}"
except Exception:
pass

raise RuntimeError(
f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
"This may be due to temporary service issues."
)
elif response.status_code == 400:

try:
text = response.text
except UnicodeDecodeError:
text = response.content.decode("utf-8", errors="replace")
response_preview = self._truncate_response(text)

if response.status_code == 400:
raise ValueError(
f"Invalid request ({response.status_code}): {response.reason_phrase}. "
f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
response = await self._client.post(url, json={"text": text})

if not response.is_success:
response_preview = self._truncate_response(response.text)
if 500 <= response.status_code < 600:
error_details = ""
try:
error_json = response.json()
if isinstance(error_json, dict) and "error" in error_json:
error_details = f" {error_json['error']}"
except Exception:
pass

raise RuntimeError(
f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
"This may be due to temporary service issues."
)

try:
text = response.text
except UnicodeDecodeError:
text = response.content.decode("utf-8", errors="replace")
response_preview = self._truncate_response(text)

raise RuntimeError(
f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
return {"email": payload["email"], "id": payload["id"]}

if 500 <= response.status_code < 600:
response_preview = self._truncate_response(response.text)
error_details = ""
try:
error_json = response.json()
if isinstance(error_json, dict) and "error" in error_json:
error_details = f" {error_json['error']}"
except Exception:
pass

raise RuntimeError(
f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
"This may be due to temporary service issues."
)

return None
Expand Down
63 changes: 63 additions & 0 deletions tests/test_502_handling.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
"""Test that 502 errors with HTML bodies are sanitized"""
config = {"api_key": "test_key", "api_url": "https://api.test.com"}

html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
assert len(html_body) > 200 # Ensure it triggers truncation

with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
mock_response = Mock()
mock_response.is_success = False
mock_response.status_code = 502
mock_response.reason_phrase = "Bad Gateway"
mock_response.text = html_body
mock_response.json.side_effect = ValueError(
"Not JSON"
) # simulating non-JSON response
mock_post.return_value = mock_response

async with LingoDotDevEngine(config) as engine:
with pytest.raises(RuntimeError) as exc_info:
await engine.localize_text("hello", {"target_locale": "es"})

error_msg = str(exc_info.value)

# Assertions
assert "Server error (502): Bad Gateway." in error_msg
assert "This may be due to temporary service issues." in error_msg
assert "Response:" not in error_msg
assert "<html>" not in error_msg
assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.

@pytest.mark.asyncio
async def test_500_json_handling():
"""Test that 500 errors with JSON bodies are preserved"""
config = {"api_key": "test_key", "api_url": "https://api.test.com"}
error_json = {"error": "Specific internal error message"}

with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
mock_response = Mock()
mock_response.is_success = False
mock_response.status_code = 500
mock_response.reason_phrase = "Internal Server Error"
mock_response.text = json.dumps(error_json) # Needed for response_preview
mock_response.json.return_value = error_json
mock_post.return_value = mock_response

async with LingoDotDevEngine(config) as engine:
with pytest.raises(RuntimeError) as exc_info:
await engine.localize_text("hello", {"target_locale": "es"})

error_msg = str(exc_info.value)

# Assertions
assert "Server error (500): Internal Server Error." in error_msg
assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.
72 changes: 72 additions & 0 deletions tests/test_unicode_handling.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
"""Test that malformed unicode responses are handled gracefully"""
config = {"api_key": "test_key", "api_url": "https://api.test.com"}

# Invalid utf-8 sequence (0xFF)
invalid_bytes = b"\xff\xfe\xfd"

# Re-writing the test to target a successful status code (e.g. 200) but invalid body
# This triggers _safe_parse_json which is where the fix was applied
with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
mock_response = Mock()
mock_response.is_success = True
mock_response.status_code = 200
# json() raises UnicodeDecodeError
mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
# text property also raises UnicodeDecodeError
type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
# content property returns the bytes
mock_response.content = invalid_bytes

mock_post.return_value = mock_response

async with LingoDotDevEngine(config) as engine:
try:
await engine.localize_text("hello", {"target_locale": "es"})
pytest.fail("RuntimeError was not raised")
except RuntimeError as exc:
print(f"Caught expected RuntimeError: {exc}")
error_msg = str(exc)
assert "Failed to parse API response as JSON" in error_msg
assert "Response:" in error_msg
except Exception as e:
pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
"""Test that a 400 response with invalid unicode is handled safely"""
config = {"api_key": "test_key", "api_url": "https://api.test.com"}
invalid_bytes = b"\xff\xfe\xfd"

with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
mock_response = Mock()
mock_response.is_success = False
mock_response.status_code = 400
mock_response.reason_phrase = "Bad Request"
# json() raises UnicodeDecodeError
mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
# text property raises UnicodeDecodeError (simulating access to .text)
type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
# content returning bytes
mock_response.content = invalid_bytes

mock_post.return_value = mock_response

async with LingoDotDevEngine(config) as engine:
try:
# Should raise ValueError for 400
await engine.localize_text("hello", {"target_locale": "es"})
pytest.fail("ValueError was not raised")
except ValueError as exc:
error_msg = str(exc)
assert "Invalid request (400)" in error_msg
# Verify that we fell back to safe decoding
assert "Response:" in error_msg
except Exception as e:
pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

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 Closed

Hellnight2005
wants to merge
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commits into

from

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# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
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99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

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Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

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privacy statement. We’ll occasionally send you account related emails.

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to your account

 Closed

Hellnight2005
wants to merge
3
commits into

from

 Closed


# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
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99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

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 Closed

Hellnight2005
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commits into

from

 Closed


# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
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99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Closed

Hellnight2005
wants to merge
3
commits into

from

 Closed


# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
Show file tree
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Commits

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3 commits


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Hold shift + click to select a range
99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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Conversations

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

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 Closed

Hellnight2005
wants to merge
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commits into

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 Closed


# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
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99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Closed

Hellnight2005
wants to merge
3
commits into

from

 Closed


# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
Show file tree
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Commits

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3 commits


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Hold shift + click to select a range
99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923#6

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# Fix: Occasional 502 Internal Server Error Returning Raw HTML via Python SDK #1923
#6
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99957f3

fix: sanitize 502 HTML responses from error messages


Hellnight2005 Feb 4, 2026
1e7ede5

fix: handle UnicodeDecodeError when parsing API responses


Hellnight2005 Feb 4, 2026
8cfe813

fix: guard response.text access to prevent unhandled UnicodeDecodeError


Hellnight2005 Feb 4, 2026

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66 changes: 53 additions & 13 deletions
src/lingodotdev/engine.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -104,12 +104,17 @@ def _safe_parse_json(response: httpx.Response) -> Dict[str, Any]:
 """
 try:
 return response.json()
 except json.JSONDecodeError:
 preview = LingoDotDevEngine._truncate_response(response.text)
 except (json.JSONDecodeError, UnicodeDecodeError) as err:
 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")

 preview = LingoDotDevEngine._truncate_response(text)
 raise RuntimeError(
 f"Failed to parse API response as JSON (status {response.status_code}). "
 f"This may indicate a gateway or proxy error. Response: {preview}"
 )
 ) from err

 async def _localize_raw(
 self,
Expand DownExpand Up@@ -215,13 +220,27 @@ async def _localize_chunk(
 response = await self._client.post(url, json=request_data)

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )
 elif response.status_code == 400:

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 if response.status_code == 400:
 raise ValueError(
 f"Invalid request ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -461,12 +480,26 @@ async def recognize_locale(self, text: str) -> str:
 response = await self._client.post(url, json={"text": text})

 if not response.is_success:
 response_preview = self._truncate_response(response.text)
 if 500 <= response.status_code < 600:
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 try:
 text = response.text
 except UnicodeDecodeError:
 text = response.content.decode("utf-8", errors="replace")
 response_preview = self._truncate_response(text)

 raise RuntimeError(
 f"Error recognizing locale ({response.status_code}): {response.reason_phrase}. "
 f"Response: {response_preview}"
Expand DownExpand Up@@ -498,10 +531,17 @@ async def whoami(self) -> Optional[Dict[str, str]]:
 return {"email": payload["email"], "id": payload["id"]}

 if 500 <= response.status_code < 600:
 response_preview = self._truncate_response(response.text)
 error_details = ""
 try:
 error_json = response.json()
 if isinstance(error_json, dict) and "error" in error_json:
 error_details = f" {error_json['error']}"
 except Exception:
 pass

 raise RuntimeError(
 f"Server error ({response.status_code}): {response.reason_phrase}. "
f"This may be due to temporary service issues. Response: {response_preview}"
 f"Server error ({response.status_code}): {response.reason_phrase}.{error_details} "
 "This may be due to temporary service issues."
 )

 return None
Expand Down

63 changes: 63 additions & 0 deletions
tests/test_502_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
import pytest
import json
from unittest.mock import Mock, patch
from lingodotdev import LingoDotDevEngine


@pytest.mark.asyncio
async def test_502_html_handling():
 """Test that 502 errors with HTML bodies are sanitized"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 html_body = "<html><body>" + ("<h1>502 Bad Gateway</h1>" * 50) + "</body></html>"
 assert len(html_body) > 200 # Ensure it triggers truncation

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 502
 mock_response.reason_phrase = "Bad Gateway"
 mock_response.text = html_body
 mock_response.json.side_effect = ValueError(
 "Not JSON"
 ) # simulating non-JSON response
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (502): Bad Gateway." in error_msg
 assert "This may be due to temporary service issues." in error_msg
 assert "Response:" not in error_msg
 assert "<html>" not in error_msg
 assert "<body>" not in error_msg

Comment thread
coderabbitai[bot] marked this conversation as resolved.


@pytest.mark.asyncio
async def test_500_json_handling():
 """Test that 500 errors with JSON bodies are preserved"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 error_json = {"error": "Specific internal error message"}

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 500
 mock_response.reason_phrase = "Internal Server Error"
 mock_response.text = json.dumps(error_json) # Needed for response_preview
 mock_response.json.return_value = error_json
 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 with pytest.raises(RuntimeError) as exc_info:
 await engine.localize_text("hello", {"target_locale": "es"})

 error_msg = str(exc_info.value)

 # Assertions
 assert "Server error (500): Internal Server Error." in error_msg
 assert "Specific internal error message" in error_msg
Comment thread
coderabbitai[bot] marked this conversation as resolved.


72 changes: 72 additions & 0 deletions
tests/test_unicode_handling.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,72 @@
import pytest
import json
from unittest.mock import Mock, patch, PropertyMock
from lingodotdev import LingoDotDevEngine

@pytest.mark.asyncio
async def test_malformed_unicode_handling():
 """Test that malformed unicode responses are handled gracefully"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}

 # Invalid utf-8 sequence (0xFF)
 invalid_bytes = b"\xff\xfe\xfd" 

 # Re-writing the test to target a successful status code (e.g. 200) but invalid body
 # This triggers _safe_parse_json which is where the fix was applied
 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = True 
 mock_response.status_code = 200
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property also raises UnicodeDecodeError
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content property returns the bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("RuntimeError was not raised")
 except RuntimeError as exc:
 print(f"Caught expected RuntimeError: {exc}")
 error_msg = str(exc)
 assert "Failed to parse API response as JSON" in error_msg
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")

@pytest.mark.asyncio
async def test_unicode_error_in_400_response():
 """Test that a 400 response with invalid unicode is handled safely"""
 config = {"api_key": "test_key", "api_url": "https://api.test.com"}
 invalid_bytes = b"\xff\xfe\xfd"

 with patch("lingodotdev.engine.httpx.AsyncClient.post") as mock_post:
 mock_response = Mock()
 mock_response.is_success = False
 mock_response.status_code = 400
 mock_response.reason_phrase = "Bad Request"
 # json() raises UnicodeDecodeError
 mock_response.json.side_effect = UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte")
 # text property raises UnicodeDecodeError (simulating access to .text)
 type(mock_response).text = PropertyMock(side_effect=UnicodeDecodeError("utf-8", invalid_bytes, 0, 1, "invalid start byte"))
 # content returning bytes
 mock_response.content = invalid_bytes

 mock_post.return_value = mock_response

 async with LingoDotDevEngine(config) as engine:
 try:
 # Should raise ValueError for 400
 await engine.localize_text("hello", {"target_locale": "es"})
 pytest.fail("ValueError was not raised")
 except ValueError as exc:
 error_msg = str(exc)
 assert "Invalid request (400)" in error_msg
 # Verify that we fell back to safe decoding
 assert "Response:" in error_msg
 except Exception as e:
 pytest.fail(f"Caught unexpected exception: {type(e).__name__}: {e}")