[BUG] Cowork tab disabled — yukonSilver "unsupported" on Windows 11 Pro x64 (ongoing since March 2026)

[yantsevich]

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?

Cowork tab is visible but permanently disabled. The VM never attempts to boot — the app's internal platform detection incorrectly marks yukonSilver as unsupported on a fully capable Windows 11 Pro x64 system with all virtualization features enabled.

This has been happening continuously since March 20, 2026 across multiple app versions and a full clean reinstall (Squirrel → MSIX migration).

Log Output

%APPDATA%\Claude\logs\cowork_vm_node.log contains only repeated cleanup entries — no VM boot is ever attempted:

2026-03-20 12:43:36 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-26 23:32:49 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-01 08:40:20 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-10 20:41:03 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-13 14:00:15 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

What I've Tried (all unsuccessful)

• Full clean reinstall: uninstalled Claude Desktop, deleted %APPDATA%\Claude, %LOCALAPPDATA%\Claude, removed Claude_* packages, deleted CoworkVMService, rebooted, installed fresh MSIX from claude.ai/download
• Multiple app restarts and reboots
• Confirmed Hyper-V / Virtual Machine Platform / Windows Hypervisor Platform are enabled
• Issue persists across multiple app versions over 3+ weeks

Environment

• OS: Windows 11 Pro, x64
• Claude Desktop: Latest version (MSIX install, April 2026)
• Subscription: Paid (Pro)
• Virtualization: Hyper-V, VMP, WHP — all enabled
• Network: Corporate environment
• Regular Chat mode: Works perfectly — only Cowork is affected

Related Issues

• [BUG] Cowork tab not showing on Windows 11 Pro x64 — "yukonSilver" marked as unsupported + CoworkVMService cannot be removed #25136, [BUG] Cowork shows "Virtual Machine Platform not available" — yukonSilver marked as unsupported despite all virtualization features enabled #32004, [BUG] Cowork broken after auto-update to 1.1.5749 — yukonSilver marked unsupported (was working on previous version) #32837 — yukonSilver faulty platform detection
• [BUG] Cowork "Reinstall" button in banner does nothing — "Check for Updates" falsely reports latest version on Windows #28998 — Reinstall button does nothing

What Should Happen?

Cowork tab should be active and the VM should boot successfully on Windows 11 Pro x64 with all virtualization features enabled. The yukonSilver platform detection should correctly identify this system as supported.

Error Messages/Logs

2026-03-20 12:43:36 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-26 23:32:49 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-01 08:40:20 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-10 20:41:03 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-13 14:00:15 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps to Reproduce

1. Clean uninstall Claude Desktop (deleted %APPDATA%\Claude, %LOCALAPPDATA%\Claude, removed Claude_* MSIX packages, deleted CoworkVMService)
2. Reboot Windows 11 Pro x64
3. Verify all virtualization features are enabled (Hyper-V, Virtual Machine Platform, Windows Hypervisor Platform)
4. Download and install fresh Claude Desktop from claude.ai/download (MSIX installer)
5. Launch Claude Desktop — Chat works fine
6. Observe: Cowork tab is visible but disabled/greyed out, cannot be clicked
7. Check %APPDATA%\Claude\logs\cowork_vm_node.log — shows only yukonSilver not supported (status=unsupported) entries, VM never attempts to boot

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

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

Claude Code Version

N/A — Claude Desktop latest MSIX build (April 2026)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Cowork "Virtual Machine Platform not available" — yukonSilver unsupported loop on Windows 11 Home, AMD Ryzen 7 5700U #40402
2. [BUG] yukonSilver VM flagged as "unsupported" on Windows 11 Pro Build 26200 despite all requirements met - GrowthBook feature flag issue (still unresolved) #34920
3. [BUG] Cowork "yukonSilver not supported" on Windows 11 Pro 25H2 — Intel i5-1345U, all virtualization enabled #36311

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
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[JiayiRyuu]

Environment:

• OS: Windows 11 Pro 23H2 (Build 22631.6199)
• Claude Desktop: latest version from https://downloads.claude.ai/releases/win32/ClaudeSetup.exe
• Subscription: Pro

Confirmed enabled:

• ✅ Virtual Machine Platform
• ✅ Windows Hypervisor Platform
• ✅ Hyper-V
• ✅ bcdedit /enum shows hypervisorlaunchtype Auto
• ✅ Windows Update: fully up to date
• ✅ Task Manager → CPU → Virtualization: Enabled

Symptom:
Cowork tab does not appear in Claude Desktop. Only "Chat" and "Code" are visible in the sidebar.

Log (%APPDATA%\Claude\logs\cowork_vm_node.log):

2026-04-14 16:00:34 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-15 09:41:33 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-15 14:49:02 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-15 15:18:24 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps tried:

1. Enabled all required Windows features and restarted
2. Ran bcdedit /set hypervisorlaunchtype auto as Administrator and restarted
3. Fully uninstalled Claude Desktop, deleted %APPDATA%\Claude, reinstalled from official link
4. Contacted Anthropic support (Fin AI Agent) — no resolution

Same issue as described in this thread. All system prerequisites are met. Please advise on any workaround or ETA for a fix.

[scottBat]

Confirmed fix: migrate from Squirrel install to MSIX install

Had the identical yukonSilver not supported log on a Squirrel install
of Claude 1.2581.0 on Windows 11 Pro 25H2 (build 26200), Ryzen 9 5950X.

Same version (1.2581.0) installed as MSIX on a second Win 11 Pro 25H2
machine worked fine — Cowork tab present, no "unsupported" log spam.

Migration:

1. Uninstalled Squirrel Claude
2. Installed MSIX from Microsoft Store
3. Cowork tab appeared immediately, Routines also now visible

The yukonSilver platform detection appears broken in Squirrel builds
specifically. Users stuck on Squirrel installs (via legacy .exe installer
from claude.ai/download) need to explicitly migrate to MSIX.

---

Correction: migrating from Squirrel to MSIX is not a durable fix.

Observed on Windows 11:

• Legacy .exe / Squirrel install showed yukonSilver not supported log spam and did not expose Cowork/Routines correctly.
• MSIX initially fixed that: Cowork appeared and the unsupported log spam stopped.

However, the MSIX build later failed repeatedly during/after updates:

• Claude auto-updated, restarted, then failed to launch
• Windows showed: “Another program is currently using this file”
• AppModel/AppX logs showed:
  • 0x80070020
  • “Cannot create the Desktop AppX container”
• CoworkVMService was active around the time of failure

Reinstalls could also fail after uninstall with:

• 0x80073D05
• “An error occurred while deleting the package's previously existing application data”

The stale locked files were under:

• %LocalAppData%\\Packages\\Claude_...\\SystemAppData\\Helium\\User.dat
• related User.dat.LOG* / UserClasses.dat*

Reset-AppxPackage sometimes repaired the 0x80070020 state temporarily, but the issue recurred after later updates.

Current conclusion:

• Squirrel / legacy .exe builds appear to have a yukonSilver / Cowork detection problem
• MSIX builds may initially enable Cowork, but can later brick on update due to package/runtime state issues

So this appears to be at least two separate Windows packaging problems rather than “MSIX fixes Squirrel”.

[brettsjohnson]

Hitting it on Windows 11 Pro also:

2026-04-13 18:40:25 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-13 18:40:25 [info] [VM] Module loaded successfully
2026-04-15 13:57:34 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-15 13:57:36 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-15 13:57:36 [info] [VM] Module loaded successfully
2026-04-16 18:41:25 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-16 18:41:26 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-16 18:41:26 [info] [VM] Module loaded successfully
2026-04-16 19:09:00 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-16 19:09:00 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-16 19:09:00 [info] [VM] Module loaded successfully
2026-04-16 19:21:46 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-16 19:21:46 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-16 19:21:46 [info] [VM] Module loaded successfully
2026-04-16 19:24:29 [info] [logout] User navigated to /logout, stopping VM
2026-04-16 19:24:29 [info] [stopVM] stopping VM gracefully
2026-04-16 19:24:29 [error] [logout] Failed to stop VM on logout: not configured: call 'configure' first

[ozkhan1-ship-it]

Same issue here. Pro subscriber, paying monthly, unable to access Cowork.

Environment:

• OS: Windows 11 Pro 25H2 (Build 26200.7462)
• Processor: 13th Gen Intel Core i9-13900KF
• RAM: 32 GB
• Claude Desktop: Latest version
• Hyper-V: Enabled (confirmed via Get-WindowsOptionalFeature)
• Virtual Machine Platform: Enabled
• Windows Hypervisor Platform: Enabled
• Virtualization-based security: Running
• DISM health check: No component store corruption
• SFC scan: No integrity violations

Log output (%APPDATA%\Claude\logs\cowork_vm_node.log):

2026-04-17 11:27:16 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-17 11:27:16 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-17 11:27:16 [info] [VM] Module loaded successfully

This pattern repeats on every launch. The VM never attempts to boot.

What I've tried:

• Enabled Hyper-V via Windows Features GUI (reverted on reboot)
• Enabled Hyper-V via DISM (succeeded, confirmed enabled after reboot)
• Full app restart and system reboot
• Clean reinstall of Claude Desktop

Nothing works. The platform detection continues to flag yukonSilver as unsupported on a fully capable system. This is a paying feature that I cannot use. Please prioritize fixing the Windows platform detection logic.