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fix(test-server): bind to 127.0.0.1 instead of 'localhost'#40295

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yury-s wants to merge 1 commit intomicrosoft:mainfrom
yury-s:fix-40226
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fix(test-server): bind to 127.0.0.1 instead of 'localhost'#40295
yury-s wants to merge 1 commit intomicrosoft:mainfrom
yury-s:fix-40226

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@yury-s yury-s commented Apr 18, 2026

Summary

  • Default test-server --host and startHttpServer to 127.0.0.1 instead of localhost.
  • localhost resolves to ::1 first on many dual-stack setups; the Windows 11 25H2 update broke IPv6 loopback outright, leaving clients with connect ETIMEDOUT ::1:<port> (widely reported for the VSCode extension).
  • IPv4 loopback is reachable on all affected machines. Users who actually want IPv6 can still pass --host ::1 explicitly.

Fixes #40226

@yury-s
fix(test-server): bind to 127.0.0.1 instead of 'localhost'
cd24afe 
'localhost' resolution is ambiguous on dual-stack systems and prefers
'::1' first on many environments. The IPv6 loopback has proven
unreliable (recent Windows 25H2 update broke it outright for the
Playwright VS Code extension), leaving clients with
connect ETIMEDOUT ::1:<port>.

Default both the test-server CLI --host option and the internal
startHttpServer helper to IPv4 loopback, so clients can always connect.

Fixes: microsoft#40226
pavelfeldman
pavelfeldman requested changes Apr 18, 2026
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stale defender rules problem

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github-actions bot commented Apr 18, 2026

Test results for "MCP"

26 failed
❌ [chrome] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-ubuntu-latest
❌ [chromium] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-ubuntu-latest
❌ [chrome] › mcp/cli-devtools.spec.ts:184 › pick activates dashboard session @mcp-windows-latest
❌ [chrome] › mcp/dashboard.spec.ts:135 › should capture annotations via show --annotate @mcp-windows-latest
❌ [chrome] › mcp/dashboard.spec.ts:156 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest
❌ [chrome] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-windows-latest
❌ [chromium] › mcp/cli-devtools.spec.ts:184 › pick activates dashboard session @mcp-windows-latest
❌ [chromium] › mcp/dashboard.spec.ts:135 › should capture annotations via show --annotate @mcp-windows-latest
❌ [chromium] › mcp/dashboard.spec.ts:156 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest
❌ [chromium] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-windows-latest
❌ [chrome] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-macos-latest
❌ [chromium] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-macos-latest
❌ [firefox] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-ubuntu-latest
❌ [webkit] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-ubuntu-latest
❌ [firefox] › mcp/dashboard.spec.ts:135 › should capture annotations via show --annotate @mcp-windows-latest
❌ [firefox] › mcp/dashboard.spec.ts:156 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest
❌ [firefox] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-windows-latest
❌ [webkit] › mcp/dashboard.spec.ts:135 › should capture annotations via show --annotate @mcp-windows-latest
❌ [webkit] › mcp/dashboard.spec.ts:156 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest
❌ [webkit] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-windows-latest
❌ [msedge] › mcp/cli-devtools.spec.ts:184 › pick activates dashboard session @mcp-windows-latest
❌ [msedge] › mcp/dashboard.spec.ts:135 › should capture annotations via show --annotate @mcp-windows-latest
❌ [msedge] › mcp/dashboard.spec.ts:156 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest
❌ [msedge] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-windows-latest
❌ [firefox] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-macos-latest
❌ [webkit] › mcp/http.spec.ts:347 › should not allow rebinding to localhost @mcp-macos-latest

6395 passed, 976 skipped

Merge workflow run.

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github-actions bot commented Apr 18, 2026

Test results for "tests 1"

1 failed
❌ [installation tests] › playwright-electron-should-work.spec.ts:21 › electron should work @package-installations-windows-latest

7 flaky ⚠️ [installation tests] › playwright-electron-should-work.spec.ts:31 › electron should work with special characters in path `@package-installations-windows-latest`
⚠️ [chromium-library] › library/video.spec.ts:719 › screencast › should work with video+trace `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/video.spec.ts:647 › screencast › should capture full viewport `@chromium-ubuntu-22.04-node24`
⚠️ [chromium-library] › library/video.spec.ts:275 › screencast › should capture navigation `@chromium-ubuntu-22.04-node22`
⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:1080 › cli codegen › should not throw csp directive violation errors `@firefox-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-test-output.spec.ts:118 › should collapse repeated console messages for test `@ubuntu-latest-node22`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:700 › should indicate current test status `@windows-latest-node20`

39248 passed, 847 skipped

Merge workflow run.

@lucsoft
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lucsoft commented Apr 20, 2026

I don't know how to address this anywhere, but in an on going effort to replace ipv4 this seems like a step backwards?

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[Bug]: PlayWright extension for VSCode showing 'no tests have been found'

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