fix(react): Prevent lazy route handlers from updating wrong navigation span#18898
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fix(react): Prevent lazy route handlers from updating wrong navigation span#18898
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Pull request overview
This PR fixes a race condition in React Router lazy route handling where navigation spans could be incorrectly updated when users navigate away during lazy route loading.
Changes:
- Use captured navigation span consistently instead of calling
getActiveRootSpan()at resolution time inwrapPatchRoutesOnNavigation - Add
!spanJson.timestampguard to prevent updates on already-ended spans - Remove
WINDOW.locationfallback when navigation context exists buttargetPathis undefined to avoid using stale location data
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Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.
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| File | Description |
|---|---|
| packages/react/src/reactrouter-compat-utils/lazy-routes.tsx | Updated captureCurrentLocation to return null instead of falling back to WINDOW.location when inside navigation context with undefined targetPath |
| packages/react/src/reactrouter-compat-utils/instrumentation.tsx | Modified wrapPatchRoutesOnNavigation to use captured activeRootSpan consistently in both args.patch callback and completion handler, added !spanJson.timestamp checks, removed WINDOW.location fallback |
| packages/react/test/reactrouter-compat-utils/lazy-routes.test.ts | Added edge case tests for captureCurrentLocation behavior with and without navigation context |
| packages/react/test/reactrouter-compat-utils/instrumentation.test.tsx | Added unit tests for race condition fix verifying ended spans are not updated |
| dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/tests/transactions.test.ts | Added E2E tests simulating rapid navigation scenarios to validate the race condition fix |
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s1gr1d
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Jan 26, 2026
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s1gr1d
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Looks good, but I have to say the code gets harder and harder to understand 😅
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Lms24
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Jan 28, 2026
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Following up on #18346
Fixes a remaining race condition where the
args.patchcallback and completion handler inwrapPatchRoutesOnNavigationwere still callinggetActiveRootSpan()at resolution time instead of using the captured span. This caused wrong span updates when users navigated away during lazy route loading.The fix uses the captured
activeRootSpanconsistently, adds a!spanJson.timestampcheck to skip updates on ended spans, and removes theWINDOW.locationfallback. IncaptureCurrentLocation, returnsnullwhen navigation context exists buttargetPathisundefined, instead of falling back to staleWINDOW.location.Also added E2E tests that simulate rapid navigation scenarios where a slow lazy route handler completes after the user navigated elsewhere.