fix: call onerror for silently swallowed transport errors - #1529

Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom
corvid-agent:fix/transport-onerror-swallowed-errors
Closed

fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom
corvid-agent:fix/transport-onerror-swallowed-errors

Conversation

@corvid-agent

@corvid-agentcorvid-agent commented Feb 13, 2026

Copy link
Copy Markdown
Contributor

Summary

  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false

Closes#1395

Test plan

  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  • Verify onerror fires for invalid JSON request body
  • Verify onerror fires for malformed JSON-RPC messages
  • Verify onerror fires when SSE stream write fails

🤖 Generated with Claude Code

@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent requested a review from a team as a code ownerFebruary 13, 2026 05:23
@changeset-bot

changeset-botBot commented Feb 13, 2026

Copy link
Copy Markdown

🦋 Changeset detected

Latest commit: 22d4881

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

@pkg-pr-new

pkg-pr-newBot commented Feb 13, 2026

Copy link
Copy Markdown

Open in StackBlitz

@modelcontextprotocol/client

npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server

npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express

npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono

npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node

npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881

@corvid-agent

corvid-agent commented Feb 27, 2026

Copy link
Copy Markdown
ContributorAuthor

Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!

@felixweinberger

felixweinberger commented Mar 12, 2026

Copy link
Copy Markdown
Contributor

Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.

Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

No reviews

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage

2 participants

@corvid-agent@felixweinberger
, '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" + '

Skip to content
fix: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger

, '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: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger

, '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: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger

, '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: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger

, '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: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger

, '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: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger

, '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); }
})();
})();

Skip to content
fix: call onerror for silently swallowed transport errors - #1529
Closed
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Closed
fix: call onerror for silently swallowed transport errors#1529
corvid-agent wants to merge 1 commit into
modelcontextprotocol:mainfrom 
corvid-agent:fix/transport-onerror-swallowed-errors
Conversation
@corvid-agent
@corvid-agentcorvid-agent
commented
Feb 13, 2026

Copy link


Copy Markdown

Contributor
Summary
  • Nested try/catch blocks in WebStandardStreamableHTTPServerTransport.handlePostRequest were returning error responses without invoking the onerror callback, making transport errors invisible to consumers
  • JSON parsing errors (req.json() failures) now call onerror before returning the error response
  • JSON-RPC message validation errors (Zod schema parse failures) now call onerror
  • writeSSEEvent failures now call onerror instead of silently returning false
Closes#1395
Test plan
  • pnpm typecheck:all passes
  • pnpm --filter @modelcontextprotocol/server test — all 37 tests pass
  •  Verify onerror fires for invalid JSON request body
  •  Verify onerror fires for malformed JSON-RPC messages
  •  Verify onerror fires when SSE stream write fails
🤖 Generated with Claude Code
@corvid-agent@claude
fix: call onerror for silently swallowed transport errors
22d4881
Nested try/catch blocks in WebStandardStreamableHTTPServerTransport's
handlePostRequest were returning error responses without invoking the
onerror callback, making transport errors invisible to consumers.
Fixes: - JSON parsing errors (req.json() failures) now call onerror
- JSON-RPC message validation errors now call onerror
- writeSSEEvent failures now call onerror instead of silently
returning false
Closesmodelcontextprotocol#1395
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@corvid-agent
corvid-agent
requested a review
from a team
as a code ownerFebruary 13, 2026 05:23
@changeset-bot
changeset-botBot
commented
Feb 13, 2026

Copy link


Copy Markdown

🦋 Changeset detected
Latest commit: 22d4881
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 4 packages
NameType
@modelcontextprotocol/serverPatch
@modelcontextprotocol/expressPatch
@modelcontextprotocol/honoPatch
@modelcontextprotocol/nodePatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
@pkg-pr-new
pkg-pr-newBot
commented
Feb 13, 2026

Copy link


Copy Markdown

Open in StackBlitz
@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1529

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1529

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1529

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1529

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1529

commit: 22d4881
@corvid-agent
corvid-agent
commented
Feb 27, 2026

Copy link


Copy Markdown

ContributorAuthor
Friendly bump — this PR has been passing all CI checks for two weeks now. Would love to get a review when someone has a moment. Happy to address any feedback!
@felixweinberger
felixweinberger
commented
Mar 12, 2026

Copy link


Copy Markdown

Contributor
Closing in favor of #1433, which covers these call sites plus the full set from #1580 with tests. Thanks for the contribution.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers


No reviews


Assignees


No one assigned


Labels


None yet


Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

Some transport errors are silently swallowed due to missing onerror callback usage


2 participants

@corvid-agent@felixweinberger