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

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?

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:

• #28238 (same yukonSilver error, different build)
• #25136 (originally reported, marked as fixed but persists)
• #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_