Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517

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MihaZupan merged 3 commits into
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copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged

Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
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copilot/fix-threshold-exceeded-exception

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Description

The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.

Changes

Extended exception filters in both test methods to catch all three expected SocketError codes:

// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}

This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.

Original prompt

This section details on the original issue you should resolve

<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>
<issue_description>## Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343
Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution
Pull request: #124469

Error Message

Fill the error message using step by step known issues guidance.

{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}

</issue_description>

<agent_instructions>The exception thrown is

System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>

Comments on the Issue (you are @copilot in this section)

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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LGTM

MihaZupan
MihaZupan approved these changes Feb 17, 2026
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Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs Outdated
Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs Outdated
@MihaZupan
MihaZupan marked this pull request as ready for review February 17, 2026 15:57
CopilotAI review requested due to automatic review settings February 17, 2026 15:57
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MihaZupan enabled auto-merge (squash) February 17, 2026 15:57
CopilotAI changed the title [WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
CopilotAI requested a review from MihaZupanFebruary 17, 2026 16:15
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MihaZupan merged commit e02e618 into mainFeb 17, 2026
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MihaZupan deleted the copilot/fix-threshold-exceeded-exception branch February 17, 2026 19:19
@dotnet-maestrodotnet-maestroBot mentioned this pull request Feb 18, 2026
Merged
iremyux pushed a commit to iremyux/dotnet-runtime that referenced this pull request Mar 2, 2026
@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException

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, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
Merged
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged
Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
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CopilotAI
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Feb 17, 2026•

edited

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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
Comments on the Issue (you are @copilot in this section)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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ManickaP
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LGTM
MihaZupan
MihaZupan
approved these changes
Feb 17, 2026
View reviewed changes
Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

@MihaZupan
MihaZupan
marked this pull request as ready for review
February 17, 2026 15:57
CopilotAI
review requested due to automatic review settings
February 17, 2026 15:57
@MihaZupan
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enabled auto-merge (squash)
February 17, 2026 15:57
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changed the title
[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
CopilotAI
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merged commit e02e618
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93 of 97 checks passed

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@dotnet-maestrodotnet-maestroBot
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@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException


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, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
Merged
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged
Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
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Feb 17, 2026•

edited

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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
Comments on the Issue (you are @copilot in this section)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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LGTM
MihaZupan
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approved these changes
Feb 17, 2026
View reviewed changes
Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

@MihaZupan
MihaZupan
marked this pull request as ready for review
February 17, 2026 15:57
CopilotAI
review requested due to automatic review settings
February 17, 2026 15:57
@MihaZupan
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enabled auto-merge (squash)
February 17, 2026 15:57
CopilotAI
changed the title
[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
CopilotAI
requested a review
from MihaZupanFebruary 17, 2026 16:15
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merged commit e02e618
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93 of 97 checks passed

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@dotnet-maestrodotnet-maestroBot
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@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException


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, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
Merged
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged
Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
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copilot/fix-threshold-exceeded-exception
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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
Comments on the Issue (you are @copilot in this section)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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LGTM
MihaZupan
MihaZupan
approved these changes
Feb 17, 2026
View reviewed changes
Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

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marked this pull request as ready for review
February 17, 2026 15:57
CopilotAI
review requested due to automatic review settings
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[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
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merged commit e02e618
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@dotnet-maestrodotnet-maestroBot
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Mar 2, 2026
@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException


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, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
Merged
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged
Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
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Feb 17, 2026•

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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
Comments on the Issue (you are @copilot in this section)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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ManickaP
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LGTM
MihaZupan
MihaZupan
approved these changes
Feb 17, 2026
View reviewed changes
Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

@MihaZupan
MihaZupan
marked this pull request as ready for review
February 17, 2026 15:57
CopilotAI
review requested due to automatic review settings
February 17, 2026 15:57
@MihaZupan
MihaZupan
enabled auto-merge (squash)
February 17, 2026 15:57
CopilotAI
changed the title
[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
CopilotAI
requested a review
from MihaZupanFebruary 17, 2026 16:15
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merged commit e02e618
into
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93 of 97 checks passed

@MihaZupan
MihaZupan
deleted the

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February 17, 2026 19:19
@dotnet-maestrodotnet-maestroBot
mentioned this pull request
Feb 18, 2026
 Merged

iremyux pushed a commit
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that referenced
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Mar 2, 2026
@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException


4 participants

@ManickaP@MihaZupan

, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
Merged
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged
Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Conversation
CopilotAI
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Feb 17, 2026•

edited

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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
Comments on the Issue (you are @copilot in this section)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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LGTM
MihaZupan
MihaZupan
approved these changes
Feb 17, 2026
View reviewed changes
Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
Outdated

@MihaZupan
MihaZupan
marked this pull request as ready for review
February 17, 2026 15:57
CopilotAI
review requested due to automatic review settings
February 17, 2026 15:57
@MihaZupan
MihaZupan
enabled auto-merge (squash)
February 17, 2026 15:57
CopilotAI
changed the title
[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
CopilotAI
requested a review
from MihaZupanFebruary 17, 2026 16:15
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merged commit e02e618
into
mainFeb 17, 2026

93 of 97 checks passed

@MihaZupan
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deleted the

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branch
February 17, 2026 19:19
@dotnet-maestrodotnet-maestroBot
mentioned this pull request
Feb 18, 2026
 Merged

iremyux pushed a commit
to iremyux/dotnet-runtime
that referenced
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Mar 2, 2026
@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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Successfully merging this pull request may close these issues.

[HTTP] ThresholdExceeded_ThrowsException


4 participants

@ManickaP@MihaZupan

, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
Merged
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Feb 17, 2026
Merged
Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
mainfrom 
copilot/fix-threshold-exceeded-exception
Conversation
CopilotAI
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Feb 17, 2026•

edited

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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
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Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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LGTM
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Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
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Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
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[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
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[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException


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, '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 flaky MaxResponseHeadersLength tests by handling additional SocketError codes - #124517
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copilot/fix-threshold-exceeded-exception
Feb 17, 2026
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Fix flaky MaxResponseHeadersLength tests by handling additional SocketError codes#124517
MihaZupan merged 3 commits into
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copilot/fix-threshold-exceeded-exception
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Description
The ThresholdExceeded_ThrowsException and LargeSingleHeader_ThrowsException tests were flaking when the client forcibly closed the connection after detecting excessive response headers, but before the server finished writing. The server-side loopback only handled SocketError.Shutdown, missing ConnectionReset and ConnectionAborted which manifest on different platforms/timings for the same race condition.
Changes
Extended exception filters in both test methods to catch all three expected SocketError codes:
// Beforecatch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&se.SocketErrorCode==SocketError.Shutdown){}// After catch(IOExceptionex)when(ex.InnerExceptionisSocketExceptionse&&(se.SocketErrorCode==SocketError.Shutdown||se.SocketErrorCode==SocketError.ConnectionReset||se.SocketErrorCode==SocketError.ConnectionAborted)){}
This aligns with the existing pattern in LoopbackProxyServer.cs which already handles both ConnectionReset and ConnectionAborted together.
Original prompt
This section details on the original issue you should resolve
<issue_title>[HTTP] ThresholdExceeded_ThrowsException</issue_title>

<issue_description>## Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1296343

Build error leg or test failing: System.Net.Http.Functional.Tests.WorkItemExecution

Pull request: #124469
Error Message
Fill the error message using step by step known issues guidance.
{
"ErrorMessage": "",
"ErrorPattern": "ThresholdExceeded_ThrowsException.*\[FAIL\]",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
</issue_description>
<agent_instructions>The exception thrown is
System.IO.IOException : Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host..
---- System.Net.Sockets.SocketException : An existing connection was forcibly closed by the remote host.
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(Byte[] response) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 762
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseBodyAsync(Byte[] content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 1018
at System.Net.Test.Common.GenericLoopbackConnection.SendResponseBodyAsync(String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs:line 172
at System.Net.Test.Common.LoopbackServer.Connection.SendResponseAsync(HttpStatusCode statusCode, IList`1 headers, String content, Boolean isFinal) in /_/src/libraries/Common/tests/System/Net/Http/LoopbackServer.cs:line 966
at System.Net.Http.Functional.Tests.HttpClientHandler_MaxResponseHeadersLength_Test.<>c__DisplayClass6_0.<ThresholdExceeded_ThrowsException>b__1(GenericLoopbackServer server)

Fix the test to account for this being a possibility</agent_instructions>
Comments on the Issue (you are @copilot in this section)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
@MihaZupan
Fix ThresholdExceeded_ThrowsException test to handle ConnectionReset …
de2c9d8
…and ConnectionAborted
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
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LGTM
MihaZupan
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Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
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Comment threadsrc/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
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review requested due to automatic review settings
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[WIP] Fix threshold exceeded exception in HTTP testsFix flaky MaxResponseHeadersLength tests by handling additional SocketError codesFeb 17, 2026
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@MihaZupan@iremyux
[WIP] Fix threshold exceeded exception in HTTP tests (dotnet#124517)
637adf7
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MihaZupan <25307628+MihaZupan@users.noreply.github.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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[HTTP] ThresholdExceeded_ThrowsException


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