[BUG] Claude Desktop v1.1.5368 - Cowork tab freezes UI on Windows (VM boots successfully but Electron main thread hangs)

Resolved 💬 4 comments Opened Mar 8, 2026 by homemadev Closed Apr 5, 2026

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?

<html>
<body>
<html><head></head><body><h2>Preflight Checklist</h2>
<ul>
<li>[x] I have searched existing issues and this hasn't been reported yet</li>
<li>[x] This is a single bug report (please file separate reports for different bugs)</li>
<li>[x] I am using the latest version of Claude Code</li>
</ul>
<h2>What's Wrong?</h2>
<p>Claude Desktop v1.1.5368 on Windows becomes completely unresponsive ("Not Responding") whenever the Cowork tab is activated. The Cowork VM actually boots successfully and processes spawn correctly, but the Electron UI main thread hangs and never recovers. Chat mode works perfectly — the freeze only occurs when switching to or launching in Cowork mode.</p>
<p>This makes Cowork — and all scheduled tasks — completely inaccessible, even though the backend is fully functional.</p>
<h2>Environment</h2>

<h2>Steps to Reproduce</h2>
<ol>
<li>Launch Claude Desktop v1.1.5368 on Windows</li>
<li>Click the Cowork tab (or have <code>sidebarMode</code> set to <code>"task"</code> in config)</li>
<li>The UI renders briefly, then the title bar shows "Not Responding"</li>
<li>The app never recovers — must be force-killed via Task Manager</li>
</ol>
<h2>Expected Behavior</h2>
<p>Cowork tab should load and become interactive, with the VM starting in the background without blocking the UI thread.</p>
<h2>Actual Behavior</h2>
<p>The Electron UI freezes permanently when Cowork is activated. The VM boots successfully in the background (confirmed by logs), but the UI never becomes responsive.</p>
<h2>Key Diagnostic Evidence</h2>
<h3>1. VM boots successfully but UI hangs</h3>
<p><code>main.log</code> ends at the VM startup call and never progresses:</p>
<pre><code>2026-03-08 12:51:46 [info] [VMCLIRunner] Ensuring VM is started
</code></pre>
<p>No further UI-thread activity after this line. The app is frozen.</p>
<h3>2. VM backend is fully operational</h3>
<p><code>cowork_vm_node.log</code> shows the VM boots, spawns processes, and completes tasks:</p>
<pre><code>2026-03-08 13:11:21 [info] [VM:start] Startup complete, total time: 76044ms
2026-03-08 13:11:21 [info] [Keepalive] Starting (interval=2000ms)
2026-03-08 13:12:05 [info] [Spawn:vm] id=aad7aae4... Spawn succeeded in 731ms
</code></pre>
<p>The VM runs for ~68 seconds, the process exits cleanly (<code>code=0, oom=false</code>), but the UI remains frozen throughout.</p>
<h3>3. Marketplace plugin error (possibly related)</h3>
<pre><code>2026-03-08 13:11:24 [info] operation: 'add_marketplace',
2026-03-08 13:11:24 [info] status: 'error',
2026-03-08 13:11:24 [info] error_message: 'Failed to find newly added marketplace'
</code></pre>
<h3>4. Chrome native host file lock (every launch)</h3>
<p>On every startup, this error repeats:</p>
<pre><code>[error] [Chrome Extension MCP] Failed to copy native host binary: Error: EBUSY: resource busy or locked,
copyfile '...\chrome-native-host.exe' -> '...\ChromeNativeHost\chrome-native-host.exe'
</code></pre>
<p>This persists even with Chrome fully closed and the file manually deleted.</p>
<h3>5. Chat mode works perfectly</h3>
<p>When <code>sidebarMode</code> is set to <code>"chat"</code> and IndexedDB/Session Storage are cleared, the app loads and functions normally. The freeze ONLY occurs when the Cowork tab is activated.</p>
<h2>Troubleshooting Already Attempted</h2>
<p>All of the following were tried without resolving the issue:</p>
<ul>
<li>Multiple Windows reboots</li>
<li>Force-killing all Claude and Chrome processes before launch</li>
<li>Deleting and re-downloading <code>vm_bundles</code> (VM re-downloaded 2.2GB rootfs successfully)</li>
<li>Deleting <code>claude-code-vm</code> folder (binary updated from 2.1.51 to 2.1.63 successfully)</li>
<li>Removing <code>chrome-native-host.exe</code> to resolve EBUSY lock</li>
<li>Clearing <code>Session Storage</code> and <code>Local Storage</code> (IndexedDB)</li>
<li>Clearing <code>IndexedDB</code> entirely</li>
<li>Setting <code>sidebarMode</code> to <code>"chat"</code> in <code>claude_desktop_config.json</code> (app overrides from stored session state)</li>
<li>Launching without Chrome running</li>
<li>Renaming <code>Crashpad</code> and <code>sentry</code> directories</li>
</ul>
<h2>Impact</h2>
<ul>
<li>Cowork is completely unusable</li>
<li>Scheduled tasks are inaccessible (they only appear in the Cowork sidebar)</li>
<li>17 persisted sessions and scheduled tasks are confirmed intact on disk but cannot be accessed through the UI</li>
<li>Paying subscriber cannot use the feature they're paying for</li>
</ul>
<h2>Additional Context</h2>
<ul>
<li>The <code>sidebarMode: "chat"</code> config setting is overridden by the app restoring its last URL from IndexedDB (<code>claude.ai/task/new</code>), automatically switching back to Cowork mode and triggering the freeze</li>
<li>The 76-second VM startup appears to be blocking the Electron main thread synchronously rather than running asynchronously</li>
<li>Data path for MSIX install: <code>%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\</code></li>
<li>Full <code>main.log</code> and <code>cowork_vm_node.log</code> available on request</li>
</ul>
<h2>Model</h2>
<p>Claude Sonnet 4.6</p>
<h2>Did this work before?</h2>
<p>Yes — Cowork was functional on this same system prior to this issue. Last successful Cowork session was 2026-03-07.</p></body></html>
</body>
</html>

What Should Happen?

Error Messages/Logs

## 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?

Claude Desktop v1.1.5368 on Windows becomes completely unresponsive ("Not Responding") whenever the Cowork tab is activated. The Cowork VM actually boots successfully and processes spawn correctly, but the Electron UI main thread hangs and never recovers. Chat mode works perfectly — the freeze only occurs when switching to or launching in Cowork mode.

This makes Cowork — and all scheduled tasks — completely inaccessible, even though the backend is fully functional.

## Environment

| Detail | Value |
|--------|-------|
| App Version | 1.1.5368 (d12d0218) |
| Install Type | MSIX (Microsoft Store) |
| Platform | Windows, win32 x64 |
| OS Version | 10.0.26200 |
| CPU | Intel(R) Core(TM) Ultra 7 255H |
| RAM | 64 GB (68137205760 bytes) |
| Free Memory at Crash | ~41-46 GB |
| Hyper-V Host Compute Service (vmcompute) | Running |
| Claude Code Desktop Binary | 2.1.63 (current) |

## Steps to Reproduce

1. Launch Claude Desktop v1.1.5368 on Windows
2. Click the Cowork tab (or have `sidebarMode` set to `"task"` in config)
3. The UI renders briefly, then the title bar shows "Not Responding"
4. The app never recovers — must be force-killed via Task Manager

## Expected Behavior

Cowork tab should load and become interactive, with the VM starting in the background without blocking the UI thread.

## Actual Behavior

The Electron UI freezes permanently when Cowork is activated. The VM boots successfully in the background (confirmed by logs), but the UI never becomes responsive.

## Key Diagnostic Evidence

### 1. VM boots successfully but UI hangs

`main.log` ends at the VM startup call and never progresses:

2026-03-08 12:51:46 [info] [VMCLIRunner] Ensuring VM is started

No further UI-thread activity after this line. The app is frozen.

### 2. VM backend is fully operational

`cowork_vm_node.log` shows the VM boots, spawns processes, and completes tasks:

2026-03-08 13:11:21 [info] [VM:start] Startup complete, total time: 76044ms
2026-03-08 13:11:21 [info] [Keepalive] Starting (interval=2000ms)
2026-03-08 13:12:05 [info] [Spawn:vm] id=aad7aae4... Spawn succeeded in 731ms


The VM runs for ~68 seconds, the process exits cleanly (`code=0, oom=false`), but the UI remains frozen throughout.

### 3. Marketplace plugin error (possibly related)


2026-03-08 13:11:24 [info] operation: 'add_marketplace',
2026-03-08 13:11:24 [info] status: 'error',
2026-03-08 13:11:24 [info] error_message: 'Failed to find newly added marketplace'


### 4. Chrome native host file lock (every launch)

On every startup, this error repeats:

[error] [Chrome Extension MCP] Failed to copy native host binary: Error: EBUSY: resource busy or locked,
copyfile '...\chrome-native-host.exe' -> '...\ChromeNativeHost\chrome-native-host.exe'


This persists even with Chrome fully closed and the file manually deleted.

### 5. Chat mode works perfectly

When `sidebarMode` is set to `"chat"` and IndexedDB/Session Storage are cleared, the app loads and functions normally. The freeze ONLY occurs when the Cowork tab is activated.

## Troubleshooting Already Attempted

All of the following were tried without resolving the issue:

- Multiple Windows reboots
- Force-killing all Claude and Chrome processes before launch
- Deleting and re-downloading `vm_bundles` (VM re-downloaded 2.2GB rootfs successfully)
- Deleting `claude-code-vm` folder (binary updated from 2.1.51 to 2.1.63 successfully)
- Removing `chrome-native-host.exe` to resolve EBUSY lock
- Clearing `Session Storage` and `Local Storage` (IndexedDB)
- Clearing `IndexedDB` entirely
- Setting `sidebarMode` to `"chat"` in `claude_desktop_config.json` (app overrides from stored session state)
- Launching without Chrome running
- Renaming `Crashpad` and `sentry` directories

## Impact

- Cowork is completely unusable
- Scheduled tasks are inaccessible (they only appear in the Cowork sidebar)
- 17 persisted sessions and scheduled tasks are confirmed intact on disk but cannot be accessed through the UI
- Paying subscriber cannot use the feature they're paying for

## Additional Context

- The `sidebarMode: "chat"` config setting is overridden by the app restoring its last URL from IndexedDB (`claude.ai/task/new`), automatically switching back to Cowork mode and triggering the freeze
- The 76-second VM startup appears to be blocking the Electron main thread synchronously rather than running asynchronously
- Data path for MSIX install: `%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\`
- Full `main.log` and `cowork_vm_node.log` available on request

## Model

Claude Sonnet 4.6

## Did this work before?

Yes — Cowork was functional on this same system prior to this issue. Last successful Cowork session was 2026-03-07.

Steps to Reproduce

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.1.5368 (d12d0218)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_

View original on GitHub ↗

This issue has 4 comments on GitHub. Read the full discussion on GitHub ↗