Claude Desktop 1.1.4088.0 — Multiple Critical Bugs on Windows 11 25H2 (Build 26200)

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?

Hello Anthropic Support,

I am submitting this bug report after an extensive troubleshooting session using Claude.ai attempting to install and run Claude Desktop on Windows 11 25H2. I hope these findings help your engineering team identify and fix these issues for other users.

---

SYSTEM INFORMATION

• OS: Windows 11 Pro, Version 25H2, Build 26200
• Computer: Personal laptop (Dell Latitude 7430)
• Processor: Intel i7
• Claude Desktop Versions Tested: 1.1.3963.0 and 1.1.4088.0 (MSIX)
• Windows App Runtime: Microsoft.WindowsAppRuntime.1.6, Version 6000.519.329.0
• Hyper-V: Enabled
• Windows Containers: Enabled (required fix — see below)

---

BUG 1: Claude Desktop fails to launch — CoworkVMService crashes on Windows 11 25H2

Symptom: Claude Desktop installs successfully but immediately shows "We are sorry, Claude Desktop failed to launch. Please check for updates and try again."

Root Cause: The Windows Containers feature (and related HypervisorPlatform, Containers-HNS features) are not enabled by default on Windows 11 25H2 clean installs. CoworkVMService requires these features to initialize HCS DLLs. Without them, it fails with "Incorrect function" (Event ID 1, Source: CoworkVMService).

Event Viewer Details:

• Source: CoworkVMService, Event ID 1
• Message: "Incorrect function"
• Service path: C:\Program Files\WindowsApps\Claude_1.1.3963.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe
• Note: CoworkVMService runs as LocalSystem and is NOT visible in services.msc — only discoverable via PowerShell (Get-Service)

Workaround: Enable the following Windows features via PowerShell:
Enable-WindowsOptionalFeature -Online -FeatureName Containers -All
Enable-WindowsOptionalFeature -Online -FeatureName HypervisorPlatform -All

Additional fix required: After enabling Containers, a corrupted app state must also be cleared by deleting:
%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
%APPDATA%\Claude

---

BUG 2: Windows App Runtime 1.6 dependency not met on fresh Windows 11 25H2 installs

Symptom: Event Viewer shows ERROR 0x80670016 — "Bootstrapper initialization failed while looking for version 1.6 (MSIX package version >= 6000.424.1611.0)"

Workaround: Manually download and install Windows App Runtime 1.6 from:
https://aka.ms/windowsappsdk/1.6/latest/windowsappruntimeinstall-x64.exe

Suggestion: The Claude Desktop installer should check for and install this dependency automatically.

---

BUG 3: Claude Desktop fails to relaunch after being closed

Symptom: Once Claude Desktop is successfully launched and then closed (either via system tray Quit or Stop-Process), it consistently fails to relaunch with the same "failed to launch" error. The only way to relaunch is to:

1. Stop-Process -Name Claude -Force
2. Stop-Service -Name CoworkVMService -Force
3. Delete %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
4. Relaunch via shell:AppsFolder

This suggests CoworkVMService is leaving state in a bad condition on shutdown, preventing relaunch without a full reset. A system reboot also does not resolve this — the full reset sequence is required every time.

This makes Claude Desktop effectively unusable in its current state on Windows 11 25H2 as it cannot be reliably relaunched after closing.

---

BUG 4: JavaScript crash on launch — TypeError in app.asar

Symptom: When launching via PowerShell, the following error appears before the app crashes:

TypeError: Cannot read properties of undefined (reading 'value')
at formatProperty (node:internal/util/inspect:2280:12)
at formatRaw (node:internal/util/inspect:1176:9)
at i._splat (C:\Program Files\WindowsApps\Claude_1.1.3963.0_x64__pzs8sxrjxfjjc\app\resources\app.asar\.vite\build\index.js:65:5632)

This crash occurs before any log files are written (main.log is 0 bytes or missing entirely), making it very difficult to diagnose without running from the command line.

---

BUG 5: MCP config file location inconsistency

Symptom: Claude Desktop reads the MCP config file from %APPDATA%\Roaming\Claude\claude_desktop_config.json according to the Edit Config button, but the MSIX sandbox also maintains a separate copy at %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\claude_desktop_config.json. It is unclear which location takes precedence, and the Edit Config button shows a "Location is not available" error when the Roaming\Claude folder doesn't exist.

Suggestion: Claude Desktop should automatically create the %APPDATA%\Roaming\Claude folder and a default claude_desktop_config.json on first launch.

---

BUG 6: No graceful fallback when CoworkVMService fails

Symptom: When CoworkVMService fails to initialize, the entire app crashes rather than launching in a chat-only mode. This means users with virtualization limitations (corporate policies, unsupported hardware, etc.) cannot use Claude Desktop at all.

Suggestion: Claude Desktop should detect CoworkVMService failure and fall back to a chat-only mode rather than crashing entirely.

---

RELATED GITHUB ISSUE
This report is related to GitHub issue #25914 in the anthropics/claude-code repository, which describes the same CoworkVMService/HCS DLL initialization crash on Windows 11 25H2.

---

I hope these detailed findings are useful to your engineering team. I am happy to provide additional information or assist with testing fixes if that would be helpful.

Thank you for your time.

What Should Happen?

Desktop should install without error and be able to install MCP servers

Error Messages/Logs

see above for additional information

Steps to Reproduce

see above

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

none

Claude Code Version

1.1.4088.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

all information provided above.