[BUG] Cowork mode sandbox stuck — Bash tool fails to mount virtiofs share repeatedly (Windows)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

bash failed on resume, create, and re-resume. resume: RPC error -1: failed to mount /mnt/.virtiofs-root/shared/c/... as outputs: source path ... is under Plan9 share "c" which is not mounted; create: RPC error -1: ensure user: user <session-id> already exists unexpectedly: uid=1416 gid=1416

What Should Happen?

The Bash tool (mcp__workspace__bash) should successfully mount the session's outputs/uploads folders from the local Windows drive (C:) into the Linux sandbox, so that scripts (e.g. Python/openpyxl) can read and write files in the connected workspace folder. A scheduled task that reads an Excel master DB, generates new statement files, and writes back to the workspace folder should complete without manual intervention. If a mount transiently fails, the tool should recover automatically on retry rather than failing identically 5 times in a row within the same session, and restarting the Claude app or rebooting the OS should be sufficient to restore a working sandbox.

Error Messages/Logs

bash failed on resume, create, and re-resume. resume: RPC error -1: failed to mount /mnt/.virtiofs-root/shared/c/Users/user/AppData/Local/Packages/Claude_pzs8sxrjxfjjc/LocalCache/Roaming/Claude/local-agent-mode-sessions/7719ff93-0c58-41b6-8386-154b039b3089/3c6e1ff9-466d-4ed8-8ab0-fc3b19663b38/local_4a862ab6-8937-4e83-a21c-cdb87251b21d/outputs as outputs: source path /mnt/.virtiofs-root/shared/c/Users/user/AppData/Local/Packages/Claude_pzs8sxrjxfjjc/LocalCache/Roaming/Claude/local-agent-mode-sessions/7719ff93-0c58-41b6-8386-154b039b3089/3c6e1ff9-466d-4ed8-8ab0-fc3b19663b38/local_4a862ab6-8937-4e83-a21c-cdb87251b21d/outputs is under Plan9 share "c" which is not mounted; create: RPC error -1: ensure user: user adoring-lucid-faraday already exists unexpectedly: uid=1416 gid=1416

Steps to Reproduce

Open a Cowork mode session in the Claude desktop app, with a local folder connected (e.g. Desktop\자동화).
In that session, have a scheduled task registered that manipulates files in the workspace folder (a Python script reading/writing an Excel file), then trigger that task. (Alternatively, just make any chat request that invokes the mcp__workspace__bash tool.)
The Bash tool fails with the following error:
bash failed on resume, create, and re-resume. resume: RPC error -1: failed to mount /mnt/.virtiofs-root/shared/c/... as outputs: source path ... is under Plan9 share "c" which is not mounted; create: RPC error -1: ensure user: user <session-id> already exists unexpectedly: uid=1416 gid=1416
Retry the Bash tool call in the same session — the identical error recurs (reproduced 5 times in a row).
By contrast, file tools (Read/Write/Glob) accessing the same workspace folder work normally — so file access itself is fine; only the Bash/Linux sandbox mount is failing.
Fully quit and restart the Claude desktop app — the issue persists.
Reboot Windows entirely and retry in the same session — the identical error still recurs.
(Unconfirmed) Whether opening a brand-new conversation/session resolves it has not yet been tested — if you haven't tried this yet, do so and add the result, since it would clarify whether the issue is scoped to one wedged session or is systemic.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.267

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_