[BUG] v1.1.2998.0 introduces severe instability - multiple critical failures 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?

Environment:

• OS: Windows 10
• Claude Desktop: v1.1.2998.0 (released Feb 13, 2026)
• Previous version: v1.1.2685.0
• Installation: Microsoft Store version

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Summary:

Update v1.1.2998.0 introduced severe stability problems that make Cowork essentially unusable on Windows. Multiple critical failures occur within minutes of use, requiring constant restarts/reinstalls.

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Issues Introduced by v1.1.2998.0:

Issue A: Folder Mounting Completely Broken

Symptom:
When attempting to select a working folder, the operation fails with:

This task didn't load properly
CLI output was not valid JSON. This may indicate an error during startup. 
Output: sandbox-helper: failed to unmount host share 
(virtiofs at /mnt/.virtiofs-root: invalid argument, 
plan9 at /mnt/.virtiofs-root/shared: invalid argument)

Issue B: SDK Daemon Connection Failures

Symptom:

This task didn't load properly
sdk-daemon not connected

Frequency: Intermittent - occurs randomly after 1-5 successful requests

Impact:

• Cowork becomes unresponsive
• Requires Claude Desktop restart
• Loses work in progress

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Issue C: Socket Communication Errors

Symptom:

This task didn't load properly
failed to write length: An operation was attempted on something that is not a socket.

Frequency: Intermittent - occurs after sdk-daemon error or folder mount attempts

Impact:

• Complete communication breakdown between Claude Desktop and VM
• Requires full reinstall to temporarily fix

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Failure Pattern (Critical):

The update exhibits a consistent instability cycle:

1. Initial state: Reinstall or restart Claude Desktop
2. Brief functionality: Cowork works for 1-5 requests
3. Failure: One of the above errors occurs
4. Non-recoverable: Cowork remains broken until restart/reinstall
5. Cycle repeats: Each restart provides only temporary relief

Each failure:

• Consumes user's message/usage limits
• Wastes time requiring restarts
• Makes Cowork unreliable for any real work

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Regression Analysis:

Previous Version (v1.1.2685.0):

• ✅ Cowork worked reliably in temporary workspace mode
• ✅ No socket/daemon/mounting errors
• ✅ Stable operation (aside from VPN incompatibility - see separate report)
• ❌ Folder selection UI was greyed out (non-functional)

Current Version (v1.1.2998.0):

-

• ❌ Folder mounting completely broken (virtiofs/plan9 errors)
• ❌ SDK daemon randomly disconnects
• ❌ Socket communication failures
• ❌ Requires constant restarts/reinstalls
• ❌ Overall: Significantly worse than previous version

What Should Happen?

Cowork should be operational, stable and working folder selection should be available.

Error Messages/Logs

**Diagnostic Logs:**

VM starts successfully but then fails:

[VM:start] Startup complete, total time: 10028ms
[VM] Network status: CONNECTED
[VM] API reachability: REACHABLE

[After 1-5 requests, one of these occurs:]
sdk-daemon not connected
OR
failed to write length: An operation was attempted on something that is not a socket
OR
sandbox-helper: failed to unmount host share (virtiofs/plan9 errors)

Impact:

v1.1.2998.0 makes Cowork completely unusable for production work on Windows:

    Cannot rely on folder access (broken)
    Cannot rely on stability (random failures every few minutes)
    Cannot complete multi-step tasks (failures interrupt work)
    Wastes usage limits on failed attempts
    Extremely frustrating user experience

Urgency:

This is a critical regression. The update should be:

    Rolled back immediately, OR
    Hotfixed urgently

Users are better off on the previous version (v1.1.2685.0) despite its folder selection UI bug.

Suggested Actions:

    Immediate: Consider rolling back v1.1.2998.0 or marking it as unstable
    Urgent: Investigate virtiofs/plan9 mounting regression
    Urgent: Investigate SDK daemon connection stability
    Urgent: Investigate socket communication failures
    Testing: Implement more thorough Windows testing before releases
    User Communication: Warn Windows users about instability in v1.1.2998.0

Steps to Reproduce

Steps to Reproduce:

1. Open Cowork tab
2. Click folder selection (no longer greyed out - UI fixed)
3. Select any folder within C:\Users\[username]\
4. Observe virtiofs/plan9 mount failure

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Version 1.1.2998 (1f1d4d)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Diagnostic Logs:

VM starts successfully but then fails:

[VM:start] Startup complete, total time: 10028ms
[VM] Network status: CONNECTED
[VM] API reachability: REACHABLE

[After 1-5 requests, one of these occurs:]
sdk-daemon not connected
OR
failed to write length: An operation was attempted on something that is not a socket
OR
sandbox-helper: failed to unmount host share (virtiofs/plan9 errors)

Impact:

v1.1.2998.0 makes Cowork completely unusable for production work on Windows:

    Cannot rely on folder access (broken)
    Cannot rely on stability (random failures every few minutes)
    Cannot complete multi-step tasks (failures interrupt work)
    Wastes usage limits on failed attempts
    Extremely frustrating user experience

Urgency:

This is a critical regression. The update should be:

    Rolled back immediately, OR
    Hotfixed urgently

Users are better off on the previous version (v1.1.2685.0) despite its folder selection UI bug.

Suggested Actions:

    Immediate: Consider rolling back v1.1.2998.0 or marking it as unstable
    Urgent: Investigate virtiofs/plan9 mounting regression
    Urgent: Investigate SDK daemon connection stability
    Urgent: Investigate socket communication failures
    Testing: Implement more thorough Windows testing before releases
    User Communication: Warn Windows users about instability in v1.1.2998.0