[BUG] Cowork for windows: yukonSilver not supported

Found 3 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/24974
2. https://github.com/anthropics/claude-code/issues/25024
3. https://github.com/anthropics/claude-code/issues/24962

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

I finally got it to work. Here is the summary:

[BUG] Claude Desktop MSIX installer fails silently on Windows Enterprise with split user/admin accounts — Cowork unavailable

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Desktop

Environment

• Claude Desktop version: 1.1.2685 (f39a62)
• OS: Windows 11 Enterprise 25H2 (OS Build 26200.7623)
• Architecture: x64
• Hyper-V: Fully enabled (all components)
• Account setup: Standard user account (REDACTED_USER) with separate admin account (REDACTED_ADMIN) for elevation — common enterprise configuration

Summary

The Claude Desktop installer fails silently during the MSIX installation path on Windows Enterprise systems where the logged-in user account and the admin account used for UAC elevation are different user profiles. This prevents Cowork from being available, as Cowork requires the MSIX install (which includes CoworkVMService).

The Squirrel (EXE) install path works fine but does not include Cowork functionality.

Steps to Reproduce

1. Log in to Windows as a standard user (e.g., REDACTED_USER)
2. Download Claude Desktop installer from claude.com/download
3. Run the installer — it begins the MSIX path automatically
4. First progress bar completes (MSIX download)
5. UAC prompt appears — enter credentials for a separate admin account (e.g., REDACTED_ADMIN)
6. Second progress bar starts, halts at ~50%, then the installer exits silently with no error message
7. Claude is not installed for the standard user

Expected Behavior

The MSIX package should install for the logged-in user (REDACTED_USER), regardless of which admin account is used for UAC elevation.

Actual Behavior

The installer appears to install the MSIX under the admin account's context rather than the logged-in user. Subsequent install attempts detect a conflicting CoworkVMService from the orphaned previous install, which blocks future MSIX installations.

Detailed Installer Log Analysis

From ClaudeSetup.log, a successful MSIX install shows:

2026/02/11 14:52:38.927912 Standard user — attempting MSIX install with credential prompt
2026/02/11 14:52:41.488568 Self-elevating: Claude Setup.exe --elevated --msix-path "...\Claude-4097097947.msix" --log-path "...\ClaudeSetup.log"
2026/02/11 14:52:54.301279 Is elevated: true
2026/02/11 14:52:57.202025 Squirrel process prefix: c:\users\REDACTED_ADMIN\appdata\local\anthropicclaude\
2026/02/11 14:53:05.427158 Add-AppxPackage stdout: INSTALL_SUCCESS
2026/02/11 14:53:06.067128 === Claude Setup completed successfully ===

Note: The elevated process checks for Squirrel processes under REDACTED_ADMIN (the admin account), not REDACTED_USER (the logged-in user).

However, when the user subsequently runs the installer again (e.g., because Claude didn't appear to install correctly), the log shows:

2026/02/11 14:55:29.045773 WARNING: CoworkVMService already exists (potential conflict)
2026/02/11 14:55:29.045773 Conflicting service: true

This causes the installer to fall back to the Squirrel (EXE) path, which does not include Cowork.

Cowork VM Log

Even when the MSIX was installed, Cowork never worked. The cowork log consistently showed:

[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

And earlier versions logged:

[SwiftVM] Failed to load module: Error: Cannot find package '...\node_modules\@ant\claude-swift\js\index.js'
[Bundle:status] rootfs.img missing

Root Cause Analysis

The core issue appears to be that the MSIX installer's elevation step changes the user context to the admin account. In enterprise environments where users have separate standard and admin accounts (a very common security practice), this causes:

1. MSIX installs under the wrong profile — Get-AppxPackage shows the package registered to REDACTED_ADMIN, not REDACTED_USER
2. Orphaned CoworkVMService — The packaged service (WIN32_PACKAGED_PROCESS type) persists even after the MSIX is removed, and cannot be deleted with sc.exe delete (access denied even as admin)
3. Subsequent installs blocked — The conflicting service forces fallback to the Squirrel path
4. yukonSilver reports unsupported — Even when MSIX is present, the VM engine reports as unsupported, possibly because the MSIX and the logged-in user are mismatched

Workaround

After extensive debugging, the following workaround was found:

1. Remove the orphaned MSIX package:

``powershell
Get-AppxPackage -AllUsers -Name "Claude" | Remove-AppxPackage -AllUsers
``

1. Remove the orphaned provisioned package:

``powershell
Get-AppxProvisionedPackage -Online | Where-Object {$_.DisplayName -like "*Claude*"} | Remove-AppxProvisionedPackage -Online
`
(These two steps together remove the orphaned CoworkVMService`)

1. Remove all leftover data from both user profiles
2. Reboot
3. Run the installer as the standard user, enter admin credentials when prompted — MSIX installs successfully this time
4. However, the Squirrel install may also run and overwrite the MSIX. To use the MSIX version with Cowork, manually remove the Squirrel install folder (%LOCALAPPDATA%\AnthropicClaude) and launch via:

``
explorer.exe shell:AppsFolder\Claude_pzs8sxrjxfjjc!Claude
``

Suggested Fixes

1. The MSIX installer should install the package for the logged-in user, not the elevated admin user. Use Add-AppxPackage with appropriate user targeting.
2. The installer should handle CoworkVMService conflicts gracefully — detect and clean up orphaned services before attempting install.
3. The installer should not install both MSIX and Squirrel versions — if MSIX succeeds, the Squirrel fallback should not trigger.
4. The "Application not found" error after failed installs should be handled — provide a clear error message instead of failing silently.
5. Consider supporting the split admin account pattern explicitly — this is standard practice in enterprise environments (separate standard and admin accounts per user).

Additional Context

• A colleague on the same network, same Windows Enterprise version, same group policies (verified via whoami /groups), but using a single account with admin rights, installed Claude with Cowork successfully on the first attempt.
• The Squirrel (EXE) install via -exe flag works perfectly but does not include Cowork.
• All Hyper-V features are confirmed enabled.
• The issue is reproducible across multiple clean install attempts.

Experiencing the same issue. Cowork tab does not appear — only Chat and Code are visible.

Environment:

• Claude Desktop: v1.1.2685 (f39a62)
• Windows 11 Enterprise 25H2, Build 26200.7623
• HP ZBook Power 16 inch G11 Mobile Workstation
• Intel Core Ultra 9 185H (2.30 GHz)
• 64GB RAM, x64-based processor
• Team plan (premium seat), Cowork confirmed enabled by org admin

Virtualization features (all enabled, confirmed after reboot):

• Hyper-V ✅
• Virtual Machine Platform ✅
• Windows Hypervisor Platform ✅

No conflicting service:

C:\Windows\System32>sc query CoworkVMService
[SC] EnumQueryServicesStatus:OpenService FAILED 1060:
The specified service does not exist as an installed service.

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

2026-01-23 18:45:42 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

This has been repeating on every app launch since Jan 23, 2026.

Troubleshooting attempted:

• Signed out and back in
• Full app restart
• Reinstalled latest version as admin
• Enabled all virtualization features and rebooted
• Confirmed Cowork enabled by Team org admin
• Contacted Anthropic support (bot only, no resolution)

This is a corporate-managed machine but with full admin rights and all virtualisation features available and enabled. The VM support check appears to be incorrectly returning "unsupported" for this configuration.

Experiencing the same issue. Cowork tab does not appear — only Chat and Code are visible.

Environment:

• Claude Desktop: Version 1.1.3363 (ee4247)
• Windows 10 Pro 22H2, Build 19045.6466
• Vivobook_ASUSLaptop X7400PC_N7400PC
• CPU - 11th Gen Intel(R) Core(TM) i7-11370H @ 3.30GHz
• 16GB, x64-based processor
• Pro plan

Virtualization features (all enabled, confirmed after reboot):

• Hyper-V ✅
• Virtual Machine Platform ✅
• Windows Hypervisor Platform ✅

Hyper-V Virtual Machine Management service: Running ✅

Log output (%APPDATA%\Claude\logs\cowork_vm_node.log):
2026-02-18 07:15:00 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-18 07:16:23 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-18 07:16:24 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-18 07:22:26 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-18 07:22:26 [info] [Callbacks] Initializing VM event callbacks...
2026-02-18 07:22:26 [error] [Callbacks] Swift VM addon not available for callbacks
2026-02-18 07:22:28 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-18 07:22:30 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-18 07:22:34 [warn] [startVM] VM not supported (win32/x64), skipping

Troubleshooting attempted:

• Signed out and back in ✅
• Downloaded and installed latest app version today (Feb 18, 2026) ✅
• Enabled all virtualization features and rebooted ✅

<html>
<body>
<!--StartFragment--><h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Cowork tab missing on Windows 11 Pro x64 — yukonSilver still marked "unsupported" in v1.1.3189</h2>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Adding my report to the ongoing yukonSilver issues (#25136, #25142, #25205).</p>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">Environment</h3>
<div class="overflow-x-auto w-full px-2 mb-6">
Field | Value
-- | --
Claude Desktop | v1.1.3189 (1b7b58), 2026-02-14
OS | Windows 11 Pro x64
Subscription | Pro ($20/month)
Hyper-V | Enabled and running
vmcompute | Running
vmms | Running
vm_bundles folder | Does not exist (never downloaded)

</div>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">What's happening</h3>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">The Cowork tab does not appear in the main UI. Only "Chat" and "Code" are visible. However, <strong>Cowork is visible and configurable in Settings</strong> (see screenshot below), confirming the feature flag is active.</p>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">The VM module loads successfully but immediately skips startup due to platform detection:</p>
<div class="relative group/copy bg-bg-000/50 border-0.5 border-border-400 rounded-lg"><div class="sticky opacity-0 group-hover/copy:opacity-100 top-2 py-2 h-12 w-0 float-right"><div class="absolute right-0 h-8 px-2 items-center inline-flex z-10"><button class="inline-flex
items-center
justify-center
relative
shrink-0
can-focus
select-none
disabled:pointer-events-none
disabled:opacity-50
disabled:shadow-none
disabled:drop-shadow-none border-transparent
transition
font-base
duration-300
ease-[cubic-bezier(0.165,0.85,0.45,1)] h-8 w-8 rounded-md active:scale-95 backdrop-blur-md Button_ghost__BUAoh" type="button" aria-label="In die Zwischenablage kopieren" data-state="closed"><div class="relative"><div class="transition-all opacity-100 scale-100" style="width: 20px; height: 20px; display: flex; align-items: center; justify-content: center;"><svg width="20" height="20" viewBox="0 0 20 20" fill="currentColor" xmlns="http://www.w3.org/2000/svg" class="transition-all opacity-100 scale-100" aria-hidden="true" style="flex-shrink: 0;"><path d="M12.5 3C13.3284 3 14 3.67157 14 4.5V6H15.5C16.3284 6 17 6.67157 17 7.5V15.5C17 16.3284 16.3284 17 15.5 17H7.5C6.67157 17 6 16.3284 6 15.5V14H4.5C3.67157 14 3 13.3284 3 12.5V4.5C3 3.67157 3.67157 3 4.5 3H12.5ZM14 12.5C14 13.3284 13.3284 14 12.5 14H7V15.5C7 15.7761 7.22386 16 7.5 16H15.5C15.7761 16 16 15.7761 16 15.5V7.5C16 7.22386 15.7761 7 15.5 7H14V12.5ZM4.5 4C4.22386 4 4 4.22386 4 4.5V12.5C4 12.7761 4.22386 13 4.5 13H12.5C12.7761 13 13 12.7761 13 12.5V4.5C13 4.22386 12.7761 4 12.5 4H4.5Z"></path></svg></div><div class="absolute inset-0 flex items-center justify-center"><div class="transition-all opacity-0 scale-50" style="width: 20px; height: 20px; display: flex; align-items: center; justify-content: center;"><svg width="20" height="20" viewBox="0 0 20 20" fill="currentColor" xmlns="http://www.w3.org/2000/svg" class="transition-all opacity-0 scale-50" aria-hidden="true" style="flex-shrink: 0;"><path d="M15.1883 5.10908C15.3699 4.96398 15.6346 4.96153 15.8202 5.11592C16.0056 5.27067 16.0504 5.53125 15.9403 5.73605L15.8836 5.82003L8.38354 14.8202C8.29361 14.9279 8.16242 14.9925 8.02221 14.9989C7.88203 15.0051 7.74545 14.9526 7.64622 14.8534L4.14617 11.3533L4.08172 11.2752C3.95384 11.0811 3.97542 10.817 4.14617 10.6463C4.31693 10.4755 4.58105 10.4539 4.77509 10.5818L4.85321 10.6463L7.96556 13.7586L15.1161 5.1794L15.1883 5.10908Z"></path></svg></div></div></div></button></div></div><div class="overflow-x-auto"><pre class="code-block__code !my-0 !rounded-lg !text-sm !leading-relaxed p-3.5" style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono);"><code style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono); white-space: pre-wrap;"><span><span>2026-02-17 11:58:43 [info] [VM] Loading vmClient (TypeScript) module...
</span></span><span>2026-02-17 11:58:43 [info] [VM] Module loaded successfully
</span><span>2026-02-17 11:58:43 [info] [Callbacks] VM event callbacks initialized
</span><span>2026-02-17 11:59:00 [warn] [startVM] VM not supported (win32/x64), skipping</span></code></pre></div></div>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">The cleanup routine then marks the configuration as unsupported:</p>
<div class="relative group/copy bg-bg-000/50 border-0.5 border-border-400 rounded-lg"><div class="sticky opacity-0 group-hover/copy:opacity-100 top-2 py-2 h-12 w-0 float-right"><div class="absolute right-0 h-8 px-2 items-center inline-flex z-10"><button class="inline-flex
items-center
justify-center
relative
shrink-0
can-focus
select-none
disabled:pointer-events-none
disabled:opacity-50
disabled:shadow-none
disabled:drop-shadow-none border-transparent
transition
font-base
duration-300
ease-[cubic-bezier(0.165,0.85,0.45,1)] h-8 w-8 rounded-md active:scale-95 backdrop-blur-md Button_ghost__BUAoh" type="button" aria-label="In die Zwischenablage kopieren" data-state="closed"><div class="relative"><div class="transition-all opacity-100 scale-100" style="width: 20px; height: 20px; display: flex; align-items: center; justify-content: center;"><svg width="20" height="20" viewBox="0 0 20 20" fill="currentColor" xmlns="http://www.w3.org/2000/svg" class="transition-all opacity-100 scale-100" aria-hidden="true" style="flex-shrink: 0;"><path d="M12.5 3C13.3284 3 14 3.67157 14 4.5V6H15.5C16.3284 6 17 6.67157 17 7.5V15.5C17 16.3284 16.3284 17 15.5 17H7.5C6.67157 17 6 16.3284 6 15.5V14H4.5C3.67157 14 3 13.3284 3 12.5V4.5C3 3.67157 3.67157 3 4.5 3H12.5ZM14 12.5C14 13.3284 13.3284 14 12.5 14H7V15.5C7 15.7761 7.22386 16 7.5 16H15.5C15.7761 16 16 15.7761 16 15.5V7.5C16 7.22386 15.7761 7 15.5 7H14V12.5ZM4.5 4C4.22386 4 4 4.22386 4 4.5V12.5C4 12.7761 4.22386 13 4.5 13H12.5C12.7761 13 13 12.7761 13 12.5V4.5C13 4.22386 12.7761 4 12.5 4H4.5Z"></path></svg></div><div class="absolute inset-0 flex items-center justify-center"><div class="transition-all opacity-0 scale-50" style="width: 20px; height: 20px; display: flex; align-items: center; justify-content: center;"><svg width="20" height="20" viewBox="0 0 20 20" fill="currentColor" xmlns="http://www.w3.org/2000/svg" class="transition-all opacity-0 scale-50" aria-hidden="true" style="flex-shrink: 0;"><path d="M15.1883 5.10908C15.3699 4.96398 15.6346 4.96153 15.8202 5.11592C16.0056 5.27067 16.0504 5.53125 15.9403 5.73605L15.8836 5.82003L8.38354 14.8202C8.29361 14.9279 8.16242 14.9925 8.02221 14.9989C7.88203 15.0051 7.74545 14.9526 7.64622 14.8534L4.14617 11.3533L4.08172 11.2752C3.95384 11.0811 3.97542 10.817 4.14617 10.6463C4.31693 10.4755 4.58105 10.4539 4.77509 10.5818L4.85321 10.6463L7.96556 13.7586L15.1161 5.1794L15.1883 5.10908Z"></path></svg></div></div></div></button></div></div><div class="overflow-x-auto"><pre class="code-block__code !my-0 !rounded-lg !text-sm !leading-relaxed p-3.5" style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono);"><code style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono); white-space: pre-wrap;"><span><span>2026-02-17 11:58:40 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...</span></span></code></pre></div></div>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">The <code class="bg-text-200/5 border border-0.5 border-border-300 text-danger-000 whitespace-pre-wrap rounded-[0.4rem] px-1 py-px text-[0.9rem]">%APPDATA%\Claude\vm_bundles\</code> directory does not exist — the VM bundle was never downloaded.</p>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">What I've tried (nothing worked)</h3>
<ul class="[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2">✅ All Hyper-V features enabled (Hyper-V, VMP, WHP)</li>
<li class="whitespace-normal break-words pl-2">✅ vmcompute and vmms both running</li>
<li class="whitespace-normal break-words pl-2">✅ Logged out and back in</li>
<li class="whitespace-normal break-words pl-2">✅ Full app reinstall from claude.com/download</li>
<li class="whitespace-normal break-words pl-2">✅ App restarted multiple times</li>
<li class="whitespace-normal break-words pl-2">✅ Confirmed latest version v1.1.3189</li>
</ul>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">Hyper-V services confirmed running</h3>
<div class="relative group/copy bg-bg-000/50 border-0.5 border-border-400 rounded-lg"><div class="sticky opacity-0 group-hover/copy:opacity-100 top-2 py-2 h-12 w-0 float-right"><div class="absolute right-0 h-8 px-2 items-center inline-flex z-10"><button class="inline-flex
items-center
justify-center
relative
shrink-0
can-focus
select-none
disabled:pointer-events-none
disabled:opacity-50
disabled:shadow-none
disabled:drop-shadow-none border-transparent
transition
font-base
duration-300
ease-[cubic-bezier(0.165,0.85,0.45,1)] h-8 w-8 rounded-md active:scale-95 backdrop-blur-md Button_ghost__BUAoh" type="button" aria-label="In die Zwischenablage kopieren" data-state="closed"><div class="relative"><div class="transition-all opacity-100 scale-100" style="width: 20px; height: 20px; display: flex; align-items: center; justify-content: center;"><svg width="20" height="20" viewBox="0 0 20 20" fill="currentColor" xmlns="http://www.w3.org/2000/svg" class="transition-all opacity-100 scale-100" aria-hidden="true" style="flex-shrink: 0;"><path d="M12.5 3C13.3284 3 14 3.67157 14 4.5V6H15.5C16.3284 6 17 6.67157 17 7.5V15.5C17 16.3284 16.3284 17 15.5 17H7.5C6.67157 17 6 16.3284 6 15.5V14H4.5C3.67157 14 3 13.3284 3 12.5V4.5C3 3.67157 3.67157 3 4.5 3H12.5ZM14 12.5C14 13.3284 13.3284 14 12.5 14H7V15.5C7 15.7761 7.22386 16 7.5 16H15.5C15.7761 16 16 15.7761 16 15.5V7.5C16 7.22386 15.7761 7 15.5 7H14V12.5ZM4.5 4C4.22386 4 4 4.22386 4 4.5V12.5C4 12.7761 4.22386 13 4.5 13H12.5C12.7761 13 13 12.7761 13 12.5V4.5C13 4.22386 12.7761 4 12.5 4H4.5Z"></path></svg></div><div class="absolute inset-0 flex items-center justify-center"><div class="transition-all opacity-0 scale-50" style="width: 20px; height: 20px; display: flex; align-items: center; justify-content: center;"><svg width="20" height="20" viewBox="0 0 20 20" fill="currentColor" xmlns="http://www.w3.org/2000/svg" class="transition-all opacity-0 scale-50" aria-hidden="true" style="flex-shrink: 0;"><path d="M15.1883 5.10908C15.3699 4.96398 15.6346 4.96153 15.8202 5.11592C16.0056 5.27067 16.0504 5.53125 15.9403 5.73605L15.8836 5.82003L8.38354 14.8202C8.29361 14.9279 8.16242 14.9925 8.02221 14.9989C7.88203 15.0051 7.74545 14.9526 7.64622 14.8534L4.14617 11.3533L4.08172 11.2752C3.95384 11.0811 3.97542 10.817 4.14617 10.6463C4.31693 10.4755 4.58105 10.4539 4.77509 10.5818L4.85321 10.6463L7.96556 13.7586L15.1161 5.1794L15.1883 5.10908Z"></path></svg></div></div></div></button></div></div><div class="text-text-500 font-small p-3.5 pb-0">powershell</div><div class="overflow-x-auto"><pre class="code-block__code !my-0 !rounded-lg !text-sm !leading-relaxed p-3.5" style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono);"><code class="language-powershell" style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono); white-space: pre;"><span><span class="token token" style="color: rgb(0, 81, 194);">PS</span><span>&gt; </span><span class="token token" style="color: rgb(0, 81, 194);">Get-Service</span><span> vmcompute</span><span class="token token" style="color: rgb(43, 48, 59);">,</span><span> vmms </span><span class="token token" style="color: rgb(43, 48, 59);">|</span><span> </span><span class="token token" style="color: rgb(0, 81, 194);">Format-Table</span><span> Name</span><span class="token token" style="color: rgb(43, 48, 59);">,</span><span> Status
</span></span><span>
</span><span>Name Status
</span><span><span></span><span class="token token" style="color: rgb(20, 24, 31);">--</span><span class="token token" style="color: rgb(20, 24, 31);">--</span><span> </span><span class="token token" style="color: rgb(20, 24, 31);">--</span><span class="token token" style="color: rgb(20, 24, 31);">--</span><span class="token token" style="color: rgb(20, 24, 31);">--</span><span>
</span></span><span>vmcompute Running
</span><span>vmms Running</span></code></pre></div></div>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">Key observation</h3>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">In #26302, another user on the same version (v1.1.3189) reports that the Cowork VM now starts <strong>unconditionally</strong> — whereas previous versions logged "yukonSilver not supported, skipping". This suggests the fix is being rolled out via a server-side feature flag that has not yet reached all accounts.</p>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Additionally, the official release notes list Cowork for Pro as "macOS only" so far. If Pro on Windows is still in staged rollout, it would explain why the feature flag is active (Settings visible) but the VM platform check still blocks.</p>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">Request</h3>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Could someone from the team clarify:</p>
<ol class="[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-decimal flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2">Is Cowork on Windows currently available for <strong>Pro</strong> plan users, or only Max/Team/Enterprise?</li>
<li class="whitespace-normal break-words pl-2">If it's a staged rollout, is there an ETA for full availability on Pro + Windows?</li>
<li class="whitespace-normal break-words pl-2">Is the <code class="bg-text-200/5 border border-0.5 border-border-300 text-danger-000 whitespace-pre-wrap rounded-[0.4rem] px-1 py-px text-[0.9rem]">yukonSilver</code> platform check controlled server-side (feature flag) or client-side?</li>
</ol>
<h3 class="text-text-100 mt-2 -mb-1 text-base font-bold">Screenshots</h3>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">[Cowork visible in Settings but tab missing in main UI — screenshot attached]</p><!--EndFragment-->
</body>
</html>

<img width="763" height="537" alt="Image" src="https://github.com/user-attachments/assets/7a30f71b-171b-4904-a785-1dd3de506046" />

Confirming this bug on v1.1.3918.0.

Key detail: this is a regression — Cowork was fully working on my machine before this update. Nothing changed on my end (no OS update, no BIOS change, no feature toggle). Only the Claude Desktop auto-update broke it.

Environment: Windows 11 Pro 24H2, Intel i7-14700F, Hyper-V enabled, vmcompute/vmms/CoworkVMService all running. Log shows the same yukonSilver not supported (status=unsupported) and [startVM] VM not supported (win32/x64), skipping on repeat.

I also confirming this bug on v1.1.3918. Cowork doesn't work. I kept getting message that Virtualization is not enabled. Windows 11 Pro 24H2, intel Core Ultra 5 125H (1.2Ghz), 32GM. Hyper-V enabled, vm platform enabled, hypervisor enabled.
Log shows yukonSilver not supported (status=unsupported), checking for stale bundle.... and [startVM] VM not supported (win32/x64), skipping

Confirming on v1.1.3918.0 with a slightly different environment that may help narrow this down.

Environment:

• Claude Desktop: v1.1.3918.0 (MSIX install via Get-AppxPackage)
• Windows 11 Business 25H2, Build 26200
• Intel Core Ultra 7 255H (Arrow Lake)
• Plan: Max
• Hyper-V: enabled, vmcompute + vmms both Running
• CoworkVMService: Running (type WIN32_PACKAGED_PROCESS, no errors)
• vm_bundles directory: does not exist (bundle never downloaded)

Logs (cowork_vm_node.log):

2026-02-21 02:20:18 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-21 02:20:22 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 02:20:22 [info] [VM] Loading vmClient (TypeScript) module...
2026-02-21 02:20:22 [info] [VM] Module loaded successfully
2026-02-21 02:20:22 [info] [Callbacks] VM event callbacks initialized
2026-02-21 02:20:24 [warn] [startVM] VM not supported (win32/x64), skipping

Cowork was working fine yesterday, but after the auto-update it stopped working.

Now it shows the error: "Virtualization is not enabled. Claude's workspace requires hardware virtualization (Hyper-V)."

However, all virtualization settings are properly configured:

Hyper-V: ✅ Enabled
Windows Hypervisor Platform: ✅ Enabled
bcdedit hypervisorlaunchtype: Auto
Hyper-V services: Running
OS: Windows 11 Pro 25H2 (Build 26200)
Claude version: 1.1.3918

This appears to be a regression introduced in a recent update. Please fix this.

+1

Hyper-V Enabled.
WSL2 Enabled/working
Chat/Code working.
Docker working.
VT-d/vt-x enabled in bios
Virt machine windows components enabled
Cowork only affected components.

=== SYSTEM INFORMATION ===
Platform: win32
Architecture: x64
OS Type: Windows_NT
OS Release: 10.0.19045
OS Version: Windows 10 Pro
CPU Model: Intel(R) Core(TM) Ultra 7 265K
Asus Proart Z890

=== APP INFORMATION ===
App Name: Claude
App Version: 1.1.3918
Electron Version: 40.4.1
Chrome Version: 144.0.7559.173
Node Version: 24.13.0
V8 Version: 14.4.258.24-electron.0

<html>
<body>
<!--StartFragment--><html><head></head><body><h1>Bug Report: Claude Cowork — "Virtualization not enabled" on fully compatible Windows 11 Pro x64</h1>
<blockquote>
<p><strong>Note:</strong> Same issue as reported here, with one difference: <strong>the Cowork tab does display correctly</strong> in Claude Desktop navigation. The error only appears <em>inside</em> the Cowork tab when attempting to start the workspace, preventing any actual use of Cowork.</p>

<img width="1126" height="726" alt="Image" src="https://github.com/user-attachments/assets/03f8aec4-55f0-41bb-bd6b-30b938fff8a9" />

</blockquote>
<hr>
<p><strong>Date:</strong> 2026-02-21
<strong>Related issues:</strong> #25034, #25136, #25692</p>
<hr>
<h2>Summary</h2>
<p>Claude Cowork fails to start on a fully compatible Windows 11 Pro x64 system with Hyper-V properly enabled. The UI displays a misleading error message suggesting BIOS virtualization is disabled, while the actual root cause — confirmed by logs — is that the <code>yukonSilver</code> VM configuration is incorrectly classified as <code>unsupported</code> for the <code>win32/x64</code> platform by Claude Desktop's internal detection logic.</p>
<hr>
<h2>Environment</h2>

Property | Value
-- | --
OS | Microsoft Windows 11 Pro
OS Version | 10.0.26100 (Build 26100)
OS Edition | 24H2
Architecture | x64-based PC / 64-bit
CPU | Intel Core i5 (12th Gen, x64)
Claude Desktop Version | 1.1.3918.0 (x64)

<hr>
<h2>Windows Virtualization Features — All Enabled ✅</h2>
<p>Verified via <code>optionalfeatures</code> (Windows Features dialog):</p>
<ul>
<li><strong>Hyper-V</strong> ✅ (including all sub-components)</li>
<li><strong>Virtual Machine Platform</strong> ✅</li>
<li><strong>Windows Hypervisor Platform</strong> ✅</li>
</ul>
<p>PowerShell verification:</p>
<pre><code class="language-powershell">Get-ComputerInfo -Property "HyperV*"

HyperVisorPresent : True
HyperVRequirementDataExecutionPreventionAvailable :
HyperVRequirementSecondLevelAddressTranslation :
HyperVRequirementVirtualizationFirmwareEnabled :
HyperVRequirementVMMonitorModeExtensions :
</code></pre>
<blockquote>
<p>Note: The empty <code>HyperVRequirement</code> fields are expected and normal when Hyper-V is already running — these fields only populate when Hyper-V is NOT active.</p>
</blockquote>
<p>Windows Services:</p>
<pre><code>Name Status StartType
CoworkVMService Running Automatic
vmms Running Automatic
</code></pre>
<p>Both <code>CoworkVMService</code> and the Hyper-V Virtual Machine Management service (<code>vmms</code>) are running correctly.</p>
<hr>
<h2>Error Message Displayed in UI</h2>
<pre><code>Virtualization is not enabled
Claude's workspace requires hardware virtualization (Hyper-V).
Enable virtualization in your computer's BIOS/UEFI settings, then restart.
</code></pre>
<blockquote>
<p>This message is <strong>misleading and inaccurate</strong> — virtualization is confirmed active at both BIOS and OS level. The Cowork tab is visible and accessible, but this error is shown immediately upon entering the tab.</p>
</blockquote>
<hr>
<h2>Root Cause — <code>cowork_vm_node.log</code></h2>
<pre><code>2026-02-21 13:32:54 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-21 13:34:36 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 13:34:36 [info] [Callbacks] Initializing VM event callbacks...
2026-02-21 13:34:36 [info] [VM] Loading vmClient (TypeScript) module...
2026-02-21 13:34:36 [info] [VM] Module loaded successfully
2026-02-21 13:34:36 [info] [Callbacks] VM event callbacks initialized
2026-02-21 13:34:37 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 13:34:40 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 13:36:07 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-21 13:36:10 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 13:43:11 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-21 13:43:13 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 13:45:56 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-21 13:45:58 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-21 13:50:56 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-21 13:50:58 [warn] [startVM] VM not supported (win32/x64), skipping
[... pattern repeats on every launch attempt ...]
</code></pre>
<p>The log clearly shows that <code>yukonSilver</code> (the Cowork VM configuration) is being flagged as <code>status=unsupported</code> and skipped entirely — <strong>before any actual VM boot attempt is made</strong>. This is a platform detection logic issue inside Claude Desktop, not a hardware or OS configuration problem.</p>
<hr>
<h2>Troubleshooting Steps Attempted — All Unsuccessful</h2>
<p>The following fixes were attempted in order:</p>
<ol>
<li>
<p><strong>Enabled Hyper-V in BIOS (HP laptop UEFI settings)</strong></p>
<ul>
<li>Confirmed Intel VT-x enabled in firmware</li>
<li>Result: No change</li>
</ul>
</li>
<li>
<p><strong>Enabled all 3 Windows virtualization features</strong></p>
<ul>
<li>Hyper-V (with all sub-components)</li>
<li>Virtual Machine Platform</li>
<li>Windows Hypervisor Platform</li>
<li>Restarted after each change</li>
<li>Result: No change</li>
</ul>
</li>
<li>
<p><strong>Clean reinstall of Claude Desktop</strong></p>
<ul>
<li>Full uninstall via Windows Settings</li>
<li>Manual deletion of <code>%APPDATA%\Claude</code> directory</li>
<li>Fresh install from claude.ai/download (v1.1.3918.0)</li>
<li>Result: No change — same log pattern on first launch</li>
</ul>
</li>
<li>
<p><strong>Launched Claude Desktop as Administrator</strong></p>
<ul>
<li>Right-click → Run as administrator</li>
<li>Result: No change</li>
</ul>
</li>
<li>
<p><strong>Disabled ProtonVPN</strong></p>
<ul>
<li>In case network filtering interfered with VM detection</li>
<li>Result: No change</li>
</ul>
</li>
<li>
<p><strong>Verified CoworkVMService is running</strong></p>
<ul>
<li><code>Get-Service CoworkVMService</code> → Status: Running, StartType: Automatic</li>
<li>Result: Service is running but VM is still classified as unsupported before any boot attempt</li>
</ul>
</li>
</ol>
<hr>
<h2>Conclusion</h2>
<p>The hardware and OS configuration is fully compliant with Cowork requirements:</p>
<ul>
<li>Hyper-V is active (<code>HyperVisorPresent: True</code>)</li>
<li><code>CoworkVMService</code> is running</li>
<li>Windows 11 Pro 24H2 x64 — fully supported edition and architecture</li>
<li>Claude Desktop v1.1.3918.0 — latest available version as of 2026-02-21</li>
</ul>
<p>The failure originates entirely from Claude Desktop's internal <code>yukonSilver</code> platform detection logic incorrectly marking <code>win32/x64</code> as unsupported. The UI error message pointing to BIOS settings is a red herring that leads users through unnecessary and ineffective troubleshooting steps.</p>
<p><strong>Requested fix:</strong> Review and correct the <code>yukonSilver</code> platform detection logic for <code>win32/x64</code> on Windows 11 Pro 24H2 (Build 26100). Also consider updating the UI error message to better reflect the actual cause when the issue is a platform detection failure rather than a missing BIOS setting.</p>
<hr>
<p><em>System identifiers have been anonymized. This report was generated with the assistance of Claude Chat (claude.ai).</em></p></body></html><!--EndFragment-->
</body>
</html>

Experiencing the same issue. Fresh clean install still shows yukonSilver not supported (status=unsupported).

Environment:

• Windows 11 Pro (Build 26200), x64 (I upgraded this from Home edition to try to solve this but it didnt)
• Claude Desktop 1.x (MSIX Store install, package: Claude_pzs8sxrjxfjjc)
• Paid plan

Virtualization (all confirmed working):

• Intel VT-x enabled in BIOS
• Microsoft-Hyper-V-All: Enabled
• HypervisorPlatform: Enabled
• VirtualMachinePlatform: Enabled
• Hyper-V services (vmcompute, vmms): Running
• hypervisorlaunchtype: Auto
• WSL2 running (Ubuntu, version 2)
• Docker Desktop running (WSL2 backend)

Log (cowork_vm_node.log):
2026-02-21 10:13:21 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for
stale bundle...

When I open Cowork I get the error
Virtualization is not enabled
Claude's workspace requires hardware virtualization (Hyper-V). Enable virtualization in your computer's BIOS/UEFI settings, then restart.

What I tried (none resolved it):

1. Enabled all Hyper-V features
2. Installed WSL2 + Docker Desktop
3. Upgraded from Windows 11 Home to Pro + rebooted
4. Disabled/re-enabled Core Isolation (Memory Integrity)
5. Ran the workaround from this issue:

Get-AppxPackage -AllUsers -Name "Claude" | Remove-AppxPackage -AllUsers
Get-AppxProvisionedPackage -Online | Where-Object {$_.DisplayName -like "Claude"} | Remove-AppxProvisionedPackage
-Online

1. Deleted %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc
2. Rebooted and reinstalled Claude Desktop fresh

Fixed in v1.1.3963.0 — Cowork is working again on my machine (Windows 11 Pro 24H2, i7-14700F). Auto-update resolved the yukonSilver detection issue.

Some combo of enabling the "Containers" windows feature (not virtualization, not hyper-v) and installing straight from the msix worked for m on Win 10 Pro (+Ext support).

https://claude.ai/api/desktop/win32/x64/msix/latest/redirect.

I had to ensure all of the following were re-enabled after a windows update:

Get-WindowsOptionalFeature -Online | Where-Object {$_.FeatureName -match 'Hyper-V|VirtualMachine|Containers'} | Select FeatureName, State

(Found Containers was not enabled).

Fixed in v1.1.3963.0 — Cowork is working again on my machine (Windows 11 Pro 24H2, i7-14700F).

Official acknowledgment: https://status.claude.com/incidents/j6qqhxswnpgw

Additional diagnostic: confirmed hardware_virt_disabled root cause — WMI false negative when Hyper-V is already running

Reproduces on: Razer Blade / Intel i7-8750H / 32 GB / Windows 11 Pro for Workstations Build 26100 / Claude Desktop 1.1.3918 (a4b368)

main.log gives the explicit reason code (not just cowork_vm_node.log):

2026-02-21 20:37:22 [info] [warm] Skipping VM warm download - YukonSilver not supported (hardware_virt_disabled)

The WMI contradiction that causes it:

# Returns FALSE on this machine — expected when Hyper-V hypervisor is already running
Get-CimInstance Win32_Processor | Select-Object VirtualizationFirmwareEnabled
# → False

# Returns TRUE — hypervisor IS active
(Get-CimInstance Win32_ComputerSystem).HypervisorPresent
# → True

When Hyper-V is running, the hypervisor takes ownership of VT-x at boot. From that point on, Win32_Processor.VirtualizationFirmwareEnabled (and equivalent CPUID/firmware-query paths) return False because the OS can no longer query the hardware directly — the hypervisor has abstracted it. This is documented, expected Windows behavior. HypervisorPresent = True is the correct API to confirm a hypervisor is active.

Full environment confirmation — Hyper-V is fully operational:

Microsoft-Hyper-V-All / Microsoft-Hyper-V / Microsoft-Hyper-V-Hypervisor: Enabled
vmcompute: Running | vmms: Running | hypervisorlaunchtype: Auto
Get-VMHost: responds with real data (12 logical processors, 32 GB)

Proposed fix: In the yukonSilver platform detection function, hardware_virt_disabled should not be raised when HypervisorPresent = True. The check should be:

supported = HypervisorPresent === true
         OR (VirtualizationFirmwareEnabled === true AND Hyper-V features enabled)

Not VirtualizationFirmwareEnabled in isolation — that property is architecturally False on any machine where Hyper-V is already running.

Secondary issue (same regression, same timestamp): MCP servers show a startup race condition introduced by the same update — servers connect successfully then fire server transport closed unexpectedly within ~100ms on first Desktop launch, then recover. Both issues began simultaneously when updating from a working version to 1.1.3918. Likely the same startup-sequence regression.

Resolution confirmed: v1.1.3963 fixes the yukonSilver detection failure on this machine.

Updated environment: Claude Desktop 1.1.3963 (71a7ae) / Razer Blade i7-8750H / Windows 11 Pro for Workstations Build 26100

Cowork — fully resolved. First successful startup sequence on v1.1.3963:

2026-02-21 22:27:55 [info] rootfs.vhdx not found, downloading...
2026-02-21 22:30:09 [info] rootfs.vhdx.zst checksum validated
2026-02-21 22:30:10 [info] vmlinuz.zst checksum validated
2026-02-21 22:30:19 [info] initrd.zst checksum validated
2026-02-21 22:30:19 [info] All files ready in ...claudevm.bundle
2026-02-21 22:30:38 [info] [VM] Network status: CONNECTED
2026-02-21 22:30:38 [info] [VM] API reachability: REACHABLE
2026-02-21 22:30:41 [info] [VM:start] Startup complete, total time: 165110ms

No yukonSilver not supported or hardware_virt_disabled entries. Detection logic is corrected in this version.

MCP issue — partially resolved, clarification needed. The obsidian server startup disconnects from v1.1.3918 are no longer present in the v1.1.3963 session logs. However, MCP errors are still appearing specifically when clicking the Cowork tab. From main.log, mcp-registry and Claude in Chrome are both requested at initial app start and then again ~6 seconds later when Cowork is clicked — the Cowork-triggered initialization is showing brief errors that then recover. Whether this is a v1.1.3918 regression or pre-existing behavior on Cowork tab click is unclear without earlier logs to compare against.

Separate issue still open: Cowork session data lost across reinstall cycle. The extensive uninstall/reinstall process required to work around the v1.1.3918 regression (full cache deletion, service removal, MSIX package removal) resulted in loss of all prior Cowork workspace sessions. This is a secondary impact of the regression that the fix alone cannot recover — will file separately.

Hey folks, not going to close this out just yet but letting people know that the resolution here is better in-app messaging for _why_ cowork isn't available, something we'll hopefully be doing soon.

For now you can actually find the underlying reason in debug logs for the savvy folks out there (Help -> Troubleshooting -> Show logs).

99% of the time the reason is that you haven't switched to the build of Claude Desktop that supports cowork, you can get this build from claude.com/download - Don't worry it will handle migrating everything from the old build for you, just download it, run it and you should be good

For now you can actually find the underlying reason in debug logs for the savvy folks out there (Help -> Troubleshooting -> Show logs).

Thanks!

After reading your comment, I found the yukonSilver unsupported issue in supported-features-info.json - along with the reason being that it requires MSIX. I don't remember the exakt wording.

I managed to find, download and install from the Claude.msix, after which the Cowork tab was enabled.

Perfect, we just shipped the better in-app messaging for Cowork being disabled. You should now have a disabled Cowork with a handy tooltip explaining what you need to do, or explaining why Cowork is not supported on your system.

I had the same issue, troubleshoot it with claude actually and it did figure out that the the yukonSilver unsupported issue and tried to fix it but couldn't figure it out. eventually I had to open a case [BUG] Cowork tab shows "requires a newer installation" on Windows 11 Build 26200 — yukonSilver marked unsupported #28238
The VM compatibility check rejects Windows 11 Build 26200 as unsupported. This is similar to https://github.com/anthropics/claude-code/issues/25136 which was reportedly fixed in v1.1.2998, but the issue persists on v1.1.4088.

any advice on this?

still getting same issue

Same issue here.

Environment:

• Windows 11 Pro, Build 26200, 64-Bit
• AMD Ryzen 7 7700X
• Claude Desktop app-1.1.381 (also tested on 1.0.3218 and 1.1.351)
• WSL2 installed (Ubuntu-24.04, default version 2)
• Hypervisor detected (systeminfo confirms)

Logs (claude_vm_node.log):

[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)
[Bundle:status] rootfs.img missing
[SwiftVM] Failed to load module: Cannot find package '@ant/claude-swift'

This has persisted across multiple app versions and reinstalls. The @ant/claude-swift module has never been present in any Windows build. Cowork tab does not appear.

Update: Enabling Hyper-V fixed the issue.

Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All -All

After reboot, Cowork works without errors. The misleading error message ("VM service not running") gives no indication that Hyper-V needs to be enabled manually — a clearer error or automatic prompt would help.

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.