RPC error -1: virtiofs mount failure after ~1 hour of use on 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?

For the GitHub issue description, copy and paste exactly what you shared with me earlier:
Problem:
I'm experiencing a recurring crash with Claude Cowork on Windows. The error message is: RPC error -1: failed to ensure virtiofs mount: Plan9 mount failed: bad address
Details:
The error occurs after approximately 1 hour of use — Cowork launches and works fine, then crashes after extended use
Restarting Cowork temporarily fixes it, but the error returns after another ~45 minutes to an hour
System: Windows 11, Lenovo Legion PC
Windows features enabled: Virtual Machine Platform, Windows Hypervisor Platform, Windows Subsystem for Linux (WSL2), Windows Projected File System
I enabled WSL and Windows Projected File System based on troubleshooting suggestions — it may have extended the time before crashing but did not resolve the issue
This appears to be a memory or resource leak in the virtiofs/Plan9 layer rather than a configuration issue, since it works fine on startup but degrades over time.
That gives the developers all the technical details they need to investigate your issue.

What Should Happen?

Expected behavior:
Claude Cowork should run continuously without crashing. The virtiofs mount should remain stable during extended use sessions (multiple hours) without requiring restarts.
Current behavior:
RPC error -1 occurs after ~1 hour, requiring restart to temporarily resolve.
This tells the developers exactly what the ideal outcome should be versus what's actually happening with your setup.

Error Messages/Logs

RPC error -1: failed to ensure virtiofs mount: Plan9 mount failed: bad address

Steps to Reproduce

Install and launch Claude Cowork on Windows 11 (Lenovo Legion PC)
Begin working normally — Cowork functions without issue on startup
Continue using Cowork for approximately 45 minutes to 1 hour
After extended use, Cowork crashes with the following error:
RPC error -1: failed to ensure virtiofs mount: Plan9 mount failed: bad address
Restarting Cowork resolves the error temporarily
After another ~45 minutes to 1 hour of use, the error recurs

System configuration:

OS: Windows 11
Hardware: Lenovo Legion
Windows features enabled: Virtual Machine Platform, Windows Hypervisor Platform, Windows Subsystem for Linux (WSL2), Windows Projected File System

Note: WSL2 and Windows Projected File System were enabled during troubleshooting and may have slightly extended the time before crashing, but did not resolve the underlying issue.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

Unknown — this has been occurring since I first installed Cowork and I have not had a version that worked reliably beyond ~1 hour of use.

Claude Code Version

N/A — this issue is with Claude Cowork desktop app, not Claude Code. Version unknown.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Restarting Cowork temporarily resolves the error, suggesting a memory or resource leak in the virtiofs/Plan9 layer rather than a configuration issue. The crash consistently occurs after ~45 minutes to 1 hour of use, not on startup.
Troubleshooting already attempted:

Enabled Windows Subsystem for Linux (WSL2)
Enabled Windows Projected File System
Enabled Virtual Machine Platform and Windows Hypervisor Platform (were already enabled)
Restarting Windows temporarily extended time before crash but did not resolve it

The /bug and /doctor commands in Cowork are not functional — per Anthropic's Fin AI support agent, this is a known skills functionality issue currently shown on the status page, which is why this bug is being reported via GitHub instead.

<img width="348" height="556" alt="Image" src="https://github.com/user-attachments/assets/f5cc2743-5063-4e97-8a23-15c97361b681" />