[Due for payment 2026-02-04] Chat - Report loads infinitely when navigating to /r/undefined

[jponikarchuk]

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Version Number: 9.3.8-0
Reproducible in staging?: Yes
Reproducible in production?: No
If this was caught during regression testing, add the test name, ID and link from BrowserStack: #76012
Email or phone of affected tester (no customers): jdosnijsonisjnosi@gmail.com
Issue reported by: Applause Internal Team
Bug source: Exploratory - Significant User Experience Deterioration
Device used: Mac 26.1 / Chrome
App Component: Chat Report View

Action Performed:

1. Go to staging.new.expensify.com
2. Open any chat.
3. Send https://staging.new.expensify.com/r/undefined
4. Click on the link.

Expected Result:

Not here page will open.

Actual Result:

Report loads infinitely when navigating to https://staging.new.expensify.com/r/undefined.

Workaround:

Unknown

Platforms:

• Android: App
• Android: mWeb Chrome
• iOS: App
• iOS: mWeb Safari
• iOS: mWeb Chrome
• Windows: Chrome
• MacOS: Chrome / Safari

Screenshots/Videos

1.mp4

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Issue Owner

Current Issue Owner: @lydiabarclay

[melvin-bot]

@luacmartins recently merged #76012, but they are OOO right now, so I'll auto-assign someone else.

[melvin-bot]

Triggered auto assignment to @lydiabarclay (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details. Please add this bug to a GH project, as outlined in the SO.

[melvin-bot]

Triggered auto assignment to @neil-marcellini (DeployBlockerCash), see https://stackoverflowteams.com/c/expensify/questions/9980/ for more details.

[melvin-bot]

💬 A slack conversation has been started in #expensify-open-source

[github-actions]

👋 Friendly reminder that deploy blockers are time-sensitive ⏱ issues! Check out the open `StagingDeployCash` deploy checklist to see the list of PRs included in this release, then work quickly to do one of the following:

1. Identify the pull request that introduced this issue and revert it.
2. Find someone who can quickly fix the issue.
3. Fix the issue yourself.

[OSBotify]

🔍 Investigation Summary

Classification: Frontend bug
Causing PR: #76012 - "Improve performance of inbox page loading" by @sumo-slonik (High confidence)
Related Issues: None

Recommendation: REVERT

The PR introduced a significant change in how invalid report IDs are handled. Previously, the app would redirect away from non-existent reports. PR #76012 changed this to show a "not found" state instead, but the implementation has a bug that causes infinite loading when navigating to /r/undefined.

The shouldShowNotFoundPage logic does not properly handle the edge case where the reportID from the route is the literal string "undefined", resulting in infinite loading instead of showing the NotFound page.

Reverting PR #76012 is recommended as the safest and fastest path to unblock the deploy.

Labels: Keeping DeployBlockerCash (App deploy is blocked). No changes to labels needed.

📋 Detailed Analysis

Evidence

• The bug is staging-only and reproduces on version 9.3.8-0
• PR Improve performance of inbox page loading #76012 was merged on 2026-01-23 and is included in the current staging deploy (issue Deploy Checklist: New Expensify 2026-01-23 #80389)
• The PR description explicitly states: "Additionally, the redirect from a non-existent report has been removed, and we are now showing the not found state instead"
• The issue was auto-linked to this PR by melvin-bot

Verification

Files affected by the bug:

• src/pages/home/ReportScreen.tsx - The main report screen component
• Specifically the shouldShowNotFoundPage logic (lines 525-548)

PR #76012 modifies these exact files:

• ✓ src/pages/home/ReportScreen.tsx - Major refactoring with 104 additions, 59 deletions
• ✓ src/pages/home/hooks/useReportWasDeleted.ts - New hook added (67 lines)
• ✓ src/libs/Navigation/AppNavigator/Navigators/ReportsSplitNavigator.tsx - Navigation changes
• ✓ src/components/Navigation/NavigationTabBar/index.tsx - Tab navigation changes

Root Cause

The PR changed the behavior from redirecting away from invalid reports to showing a NotFound page. The new logic in shouldShowNotFoundPage (ReportScreen.tsx:525-548) includes:

const isInvalidReportPath = !!currentReportIDFormRoute && !isValidReportIDFromPath(currentReportIDFormRoute);

The function isValidReportIDFromPath in ReportUtils.ts explicitly rejects the string "undefined":

return !!reportIDFromPath && !["", "null", "undefined", "0", "-1"].includes(reportIDFromPath);

However, when navigating to /r/undefined, the new logic causes infinite loading instead of immediately showing the NotFound page. This appears to be a timing/state management issue introduced by the refactoring of the shouldShowNotFoundPage logic along with the new firstRender state management and the useReportWasDeleted hook.

The PR attempted to optimize performance by:

1. Removing useRef in favor of useState for firstRender
2. Adding complex memoization to the header
3. Adding a new hook to detect deleted reports
4. Changing when NotFound is shown vs when redirects happen

This refactoring introduced the regression where the string "undefined" as a reportID triggers infinite loading.