[Error] [GitHub.copilot-chat] unhandlederror-Error in extension github.copilot-chat: FAILED to handle event: Cannot read propertie...

[vs-code-engineering]

Error Message

unhandlederror-Error in extension github.copilot-chat: FAILED to handle event: Cannot read properties of undefined (reading 'startOffset')

Stack Trace

    at KOr (../src/platform/notebook/common/alternativeNotebookTextDocument.ts:398:93)
    at withNotebookChangesAndEdit (../src/platform/notebook/common/alternativeNotebookTextDocument.ts:448:8)
    at MessagePortMain.emit (node:events:509:28) [not deminified]
    at Object.emit (node:<REDACTED: user-file-path>:2:2934) [not deminified]

Raw Stack Trace (minified)

TypeError: Cannot read properties of undefined (reading 'startOffset') 	at KOr (<REDACTED: user-file-path> VS <REDACTED: user-file-path>/resources\app\extensions\copilot\dist\extension.js:3510:6193) 	at e9r (<REDACTED: user-file-path> VS <REDACTED: user-file-path>/resources\app\extensions\copilot\dist\extension.js:3510:6677) 	at <REDACTED: user-file-path> VS <REDACTED: user-file-path>/resources\app\extensions\copilot\dist\extension.js:3510:13893 <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> <REDACTED: URL> 	at MessagePortMain.emit (node:events:509:28) 	at Object.emit (node:<REDACTED: user-file-path>:2:2934)

Details

Property	Value
Bucket ID	0943b5af-a65c-6c65-0d41-f07e2a67ebfe
Extension Version	0.57.0
Last Seen	Sun Jul 19 2026 23:19:59 GMT+0000 (Coordinated Universal Time)
Platforms	win32
Product	VSCode

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This issue was automatically created from the VS Code Errors Dashboard

[vs-code-engineering]

Stable Release Anomaly Details

An automated stable-release anomaly scan (GitHub.copilot-chat v0.58.0 vs previous stable minor v0.57.0) re-detected this FAILED to handle event: Cannot read properties of undefined family on v0.58.0.

• Anomaly type: new
• Previous stable: v0.57.0
• Current stable: v0.58.0

The signature spans 2 buckets on v0.58.0, affecting ~115 users total. Representative bucket 6c29da41 (~64 users). Linked to this issue. Note: the v0.58.0 variant reports reading 'length' (this issue tracks reading 'startOffset') — same FAILED to handle event dispatch path.

Commit-range narrowing is skipped for extension-mode scans.

Generated by errors-stable-scan · 1.6K AIC · ⌖ 42.1 AIC · ⊞ 53.2K · ◷