[BUG] Cowork "requires a newer installation" on Windows 11 Enterprise 24H2 — yukonSilver unsupported on v1.1.8359.0

[cameronstirling]

Preflight Checklist

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

What's Wrong?

Fresh install of Claude Desktop v1.1.8359.0 (MSIX) on Windows 11 Enterprise 24H2 shows "Cowork requires a newer installation" banner. Clicking the Reinstall button redirects to claude.ai/download which does not resolve the issue.

Performed a full clean uninstall (removed %APPDATA%\Claude, %LOCALAPPDATA%\Claude), downloaded fresh from claude.com/download, reinstalled. Same error persists.

All virtualisation features are confirmed enabled and working (Windows Sandbox launches successfully):

• Hyper-V: Enabled
• VirtualMachinePlatform: Enabled
• Containers-DisposableClientVM (Windows Sandbox): Enabled

Log from %APPDATA%\Claude\logs\cowork_vm_node.log:

2026-03-25 23:53:16 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

The cowork_vm_node.log file is only 136 bytes — this single line is the entire log content, suggesting the VM never even attempts to start.

Steps to Reproduce:

1. Uninstall Claude Desktop completely (including %APPDATA%\Claude and %LOCALAPPDATA%\Claude)
2. Download fresh from claude.com/download (Windows x64)
3. Install and sign in (MSIX package installs as v1.1.8359.0)
4. Observe "Cowork requires a newer installation" banner
5. Clicking Reinstall redirects to broken download page

Environment:

• OS: Windows 11 Enterprise 24H2 (Build 26100.8037)
• CPU: Intel Core Ultra 7 165U (x64)
• RAM: 32GB
• Claude Desktop: v1.1.8359.0 (MSIX — confirmed via Get-AppxPackage)
• Device: Corporate-managed, user has local admin
• SignatureKind: Developer
• Status: Servicing

What Should Happen?

Cowork should launch on Windows 11 Enterprise 24H2 (Build 26100.8037) with all virtualisation features enabled. The yukonSilver platform detection should recognise this as a supported configuration.

Error Messages/Logs

2026-03-25 23:53:16 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps to Reproduce

1. Uninstall Claude Desktop completely (including %APPDATA%\Claude and %LOCALAPPDATA%\Claude)
2. Download fresh from claude.com/download (Windows x64)
3. Install and sign in (MSIX package installs as v1.1.8359.0)
4. Observe "Cowork requires a newer installation" banner
5. Clicking Reinstall redirects to claude.ai/download — page renders incorrectly (just logo and "Meet Claude" text, no download button)
6. Manually downloading from claude.com/download and reinstalling does not resolve the issue

Related Issues:

• [BUG] Cowork tab shows "requires a newer installation" on Windows 11 Build 26200 — yukonSilver marked unsupported #28238 (same yukonSilver error, different build)
• [BUG] Cowork tab not showing on Windows 11 Pro x64 — "yukonSilver" marked as unsupported + CoworkVMService cannot be removed #25136 (originally reported, marked as fixed but persists)
• [BUG] Cowork "Reinstall" button in banner does nothing — "Check for Updates" falsely reports latest version on Windows #28998 (Reinstall button does nothing)

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.1.8359.0 (Claude Desktop, MSIX)

Claude Code Version

N/A — this is a Claude Desktop Cowork issue, not Claude Code CLI

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Cowork tab shows "requires a newer installation" on Windows 11 Build 26200 — yukonSilver marked unsupported #28238
2. [BUG] Cowork: yukonSilver not supported on Windows 11 Pro Build 26200 #34027
3. [BUG] Cowork: yukonSilver unsupported on Windows 11 Insider Preview 25H2 build 26220 — VM service starts then immediately stops #30454

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
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🤖 Generated with Claude Code

[cameronstirling]

Not a duplicate. The linked issues are:

• [BUG] Cowork tab shows "requires a newer installation" on Windows 11 Build 26200 — yukonSilver marked unsupported #28238 — reported on v1.1.4088, marked as duplicate of [BUG] Cowork tab not showing on Windows 11 Pro x64 — "yukonSilver" marked as unsupported + CoworkVMService cannot be removed #25136 which was closed as "fixed in v1.1.2998". The fix clearly did not resolve the underlying issue.
• [BUG] Cowork: yukonSilver not supported on Windows 11 Pro Build 26200 #34027 and [BUG] Cowork: yukonSilver unsupported on Windows 11 Insider Preview 25H2 build 26220 — VM service starts then immediately stops #30454 — may describe similar symptoms but this report confirms the yukonSilver detection bug persists on the latest MSIX build (v1.1.8359.0) as of 26 March 2026, on a fully supported configuration (Windows 11 Enterprise 24H2, x64, Hyper-V enabled, VirtualMachinePlatform enabled, Windows Sandbox functional).

The core problem: yukonSilver platform detection is incorrectly returning status=unsupported on a configuration that meets all documented requirements. This is not a configuration issue on the user's end — every virtualisation feature is enabled and confirmed working. The VM simply never attempts to start.

Keeping this open as evidence that the previously "fixed" issue remains broken on current builds.

[cameronstirling]

Not a duplicate. The linked issues (#28238, #34027, #30454) were reported on older builds and #25136 was closed as "fixed in v1.1.2998". This report confirms the yukonSilver detection bug persists on the latest MSIX build (v1.1.8359.0) as of 26 March 2026, on a fully supported config: Windows 11 Enterprise 24H2 (Build 26100.8037), x64, Hyper-V enabled, VirtualMachinePlatform enabled, Windows Sandbox functional. Every virtualisation feature is enabled and confirmed working. The VM simply never attempts to start. Keeping this open as evidence that the previously "fixed" issue remains broken on current builds.

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.