Cannot read properties of undefined #19216

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1. RWDai

   added

   bugSomething isn't workingSomething isn't working

   on Mar 26, 2026
2. github-actions

   assigned

   adamdotdevin

   on Mar 26, 2026
3. github-actions

   added

   webRelates to opencode on web / desktopRelates to opencode on web / desktop

   needs:complianceThis means the issue will auto-close after 2 hours.This means the issue will auto-close after 2 hours.

   on Mar 26, 2026
4. github-actions commented on Mar 26, 2026

   

   github-actionsBot

   on Mar 26, 2026 – with GitHub Actions

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   This issue doesn't fully meet our contributing guidelines.

   What needs to be fixed:

   • Steps to reproduce are missing — please describe what action you were taking when this error occurred (e.g., opening a project, sending a message, etc.)
   • OpenCode version is missing — please provide the version you are using
   • Operating System is missing — please include your OS and version
   • Terminal is missing — please include your terminal if applicable

   A stack trace alone is not enough context to diagnose or reproduce the issue.

   Please edit this issue to address the above within 2 hours, or it will be automatically closed.

   ---

   This issue might be a duplicate of existing issues. Please check:

   • TypeError when reopening a project in OpenCode web #19194: Similar TypeError in OpenCode web UI when reopening a project (different property but same crash pattern)

   If you believe this was flagged incorrectly, please let a maintainer know.
5. zhongruan0522 commented on Mar 26, 2026

   

   zhongruan0522

   on Mar 26, 2026

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   I’ve encountered this issue as well. I’m currently on the latest version (1.3.2), and the error persists even after switching computers or browsers; the only time it stops is when I switch to the mobile version.

   On my other computer, I even encountered #19217.
6. bwcx-jzy commented on Mar 26, 2026

   

   bwcx-jzy

   on Mar 26, 2026

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   +1
7. scnbln commented on Mar 26, 2026

   

   scnbln

   on Mar 26, 2026

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   Same issue here — v1.3.2, opencode serve via systemd on LAN.

   Environment

   • opencode v1.3.2 (bun global install)
   • Ubuntu 24.04, Linux 6.17.0
   • opencode serve --port 4096 --hostname 0.0.0.0 as a user systemd service
   • Accessing web UI from a remote machine over LAN (http://<ip>:4096)

   Reproduction

   The error occurs consistently when opening the web UI in a browser. The exact same stack trace as reported:

   TypeError: Cannot read properties of undefined (reading 'replaceAll')
       at K (session-BdJIdAn0.js:19:84137)
       at Object.fn (session-BdJIdAn0.js:19:84224)
   

   Root cause analysis

   Traced through the minified bundle. The crash is in a SolidJS createMemo inside the session side panel that builds a file tree from diffs:

   // session-side-panel.tsx L70,L74 (minified as K)
   const normalize = (p: string) => p.replaceAll("\\\\", "/").replace(/\/+$/, "")
   // called with diff.file which is undefined

   The underlying issue is a reactive timing race in reconcile(). The event reducer uses:

   setStore("session_diff", sessionID, reconcile(props.diff, { key: "file" }))

   During reconciliation, dependent memos re-evaluate in a transient state where:

   1. diffs() itself may not yet be an array (SolidJS store proxy mid-update → .map is not a function)
   2. Individual diff items may have file: undefined (proxy object not yet populated)

   This is more likely to trigger over a network (LAN/remote access) due to WebSocket event delivery timing being less deterministic than localhost.

   Workaround

   Since the web assets are embedded in the bun-compiled binary and can't be patched directly, I set up a bun reverse proxy that intercepts session-*.js responses and applies null guards on-the-fly:

   1. Inject a safe-array helper: __sa(v) — coerces SolidJS store proxies to real arrays via Array.isArray / Array.from with try/catch fallback
   2. Guard the normalize function: K=q=>(q||"").replaceAll(...)
   3. Guard the reduceRight callback: skip items where _.file is falsy
   4. Wrap all e.diffs() call sites with __sa() (.map, .length, for...of)
   5. Guard L.file access in the <For> render callback

   The proxy runs as a separate systemd user service on :4097, forwarding to the original server on :4096. After applying these patches, the error is gone.

   Suggested fix

   All diff.file accesses in session-side-panel.tsx, session-turn.tsx, and session-review.tsx need null guards. Additionally, the memos reading diffs() should handle the case where the store value is not yet an array during reconcile() — either by adding Array.isArray checks or by using createEffect with deferred reads instead of eager createMemo.

   ---

   All debugging — minified source tracing, binary string extraction, DB inspection, server log analysis, and patch development — was performed entirely through opencode itself (TUI via opencode attach).

   👍React with 👍3Reacted by Chandler Gonzales, Guang YANG and RWDai
8. doge-liang commented on Mar 26, 2026

   

   doge-liang

   on Mar 26, 2026

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   111
9. github-actions commented on Mar 26, 2026

   

   github-actionsBot

   on Mar 26, 2026 – with GitHub Actions

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   This issue has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

   Feel free to open a new issue that follows our issue templates.
10. github-actions

    removed

    needs:complianceThis means the issue will auto-close after 2 hours.This means the issue will auto-close after 2 hours.

    on Mar 26, 2026
11. github-actions

    closed this as not plannedon Mar 26, 2026
12. krasen1234 commented on Mar 26, 2026

    

    krasen1234

    on Mar 26, 2026

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    TypeError: Cannot read properties of undefined (reading 'replaceAll')
    same issue.
13. adamcohenhillel commented on Mar 26, 2026

    

    adamcohenhillel

    on Mar 26, 2026

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    same
14. joelcomp1 commented on Mar 26, 2026

    

    joelcomp1

    on Mar 26, 2026

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    seeing this as well
15. ghiagio commented on Apr 5, 2026

    

    ghiagio

    on Apr 5, 2026

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    Same thing, I just run opencode web, and the error is the first thing loaded
16. RWDai commented on Apr 6, 2026

    

    RWDai

    on Apr 6, 2026

    Author

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    Same thing, I just run opencode web, and the error is the first thing loaded

    I can no longer reproduce this in the latest version. Try the latest version?