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Unhandled case: [object Object] banner halts agent execution mid-run #59156
Description
Version: Claude Code 2.1.140 (VS Code native extension)
OS: macOS 15 (Darwin 24.6.0)
Symptom
A red error banner reading Unhandled case: [object Object] appears at the top of the chat. When it appears, the active agent run halts and the response stream stops. The banner links to "View output logs · Troubleshooting resources."
Impact
The error has reproduced across multiple turns in the same session. Each occurrence interrupts in-flight work — long-running Bash commands, file edits, and agent tasks lose progress and have to be re-run, duplicating both time and API cost.
Likely cause
The [object Object] substring strongly suggests an unstringified Error or response object reaching a UI error handler. Calling JSON.stringify(err, Object.getOwnPropertyNames(err)), or surfacing err.message / err.stack, would at least make this diagnosable from the user side.
Repro
Not yet reduced to a minimal case — occurs during normal multi-turn agent sessions in the VS Code extension while running Bash + Python (openpyxl) workloads. A screenshot of the banner is available on request.
Ask
- Stop the error from halting agent execution (degrade gracefully so the in-flight run completes).
- Replace
[object Object]with the actual error string so users can self-diagnose or attach it to bug reports.
Activity
github-actions commentedon May 14, 2026
Found 3 possible duplicate issues:
This issue will be automatically closed as a duplicate in 3 days.
🤖 Generated with Claude Code
DanielPVG commentedon May 14, 2026
Same v2.1.141 macOS arm64 + VSCode 1.120.0 upgrade + cold start trigger.
Symptoms:
Output panel hardcoded --debug --debug-to-stderr CLI flags spawn behavior
Duplicate MCP Server activation: ports 43183 + 42615 within 5 seconds
Chat reply not rendering in webview after sending message
"[DEBUG] Org fast mode: disabled (extra_usage_disabled)" on personal Max 5x subscription
Workarounds tried: Cmd+Q quit + restart (clears duplicate processes temporarily but --debug flags remain hardcoded).
whatl3y commentedon May 20, 2026
+1
witteb-ssc commentedon Jun 18, 2026
same issue - confirmed june-17-2026
github-actions commentedon Jul 30, 2026
Closing for now — inactive for too long. Please open a new issue if this is still relevant.
github-actions commentedon Sep 23, 2026
This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.