### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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? Preflight Checklist

[BUG] Cowork: yukonSilver classified as unsupported on fully capable Windows 11 Pro x64 (i5-14600K)

Status Fixed / completed

Maintainer reply None cached

Activity 5 comments · opened Feb 21, 2026 · closed Feb 22, 2026

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?

<html>
<body>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Preflight Checklist</h2>
<ul class="contains-task-list">
<li class="task-list-item"><input disabled="" type="checkbox" checked=""> I have searched existing issues and this hasn't been reported yet</li>
<li class="task-list-item"><input disabled="" type="checkbox" checked=""> This is a single bug report</li>
<li class="task-list-item"><input disabled="" type="checkbox" checked=""> I am using the latest version of Claude Desktop</li>
</ul>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">What's Wrong?</h2>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Cowork consistently fails with <strong>"Virtualization is not enabled"</strong> error on a fully capable Windows 11 Pro x64 system. The internal <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> feature is classified as <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]">status=unsupported</code>, and the VM never attempts to boot.</p>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]"><strong>The same Anthropic account on a different PC (i3-12100, same Claude version 1.1.3918.0, same OS build 26200) works perfectly.</strong> Both PCs have identical Claude Desktop versions and GrowthBook feature counts (27 features).</p>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Root Cause Analysis</h2>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Through source code analysis of <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]">app.asar</code>, 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]">EPt()</code> function in the app performs the following checks:</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="클립보드에 복사" 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">javascript</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-javascript" style="color: rgb(20, 24, 31); background: transparent; font-family: var(--font-mono); white-space: pre;"><span><span class="token token" style="color: rgb(129, 0, 194);">function</span><span> </span><span class="token token" style="color: rgb(179, 74, 0);">EPt</span><span class="token token" style="color: rgb(43, 48, 59);">(</span><span class="token token" style="color: rgb(43, 48, 59);">)</span><span> </span><span class="token token" style="color: rgb(43, 48, 59);">{</span><span>
</span></span><span><span> </span><span class="token token" style="color: rgb(110, 118, 135);">// 1. Platform check (win32/darwin) ✅ PASS</span><span>
</span></span><span><span> </span><span class="token token" style="color: rgb(110, 118, 135);">// 2. Architecture check (x64/arm64) ✅ PASS</span><span>
</span></span><span><span> </span><span class="token token" style="color: rgb(110, 118, 135);">// 3. MSIX installation check ✅ PASS</span><span>
</span></span><span><span> </span><span class="token token" style="color: rgb(110, 118, 135);">// 4. Windows build >= 19041 ✅ PASS (build 26200)</span><span>
</span></span><span><span> </span><span class="token token" style="color: rgb(110, 118, 135);">// 5. vs().isHardwareVirtEnabled() ← ❌ SUSPECTED FAILURE</span><span>
</span></span><span><span> </span><span class="token token control-flow" style="color: rgb(129, 0, 194);">if</span><span> </span><span class="token token" style="color: rgb(43, 48, 59);">(</span><span>n </span><span class="token token" style="color: rgb(20, 24, 31);">!=</span><span> </span><span class="token token null nil" style="color: rgb(129, 0, 194);">null</span><span> </span><span class="token token" style="color: rgb(20, 24, 31);">&&</span><span> n</span><span class="token token" style="color: rgb(43, 48, 59);">.</span><span class="token token property-access">isHardwareVirtEnabled</span><span> </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>n</span><span class="token token" style="color: rgb(43, 48, 59);">.</span><span class="token token property-access" style="color: rgb(0, 81, 194);">isHardwareVirtEnabled</span><span class="token token" style="color: rgb(43, 48, 59);">(</span><span class="token token" style="color: rgb(43, 48, 59);">)</span><span class="token token" style="color: rgb(43, 48, 59);">)</span><span>
</span></span><span><span> </span><span class="token token control-flow" style="color: rgb(129, 0, 194);">return</span><span> </span><span class="token token" style="color: rgb(43, 48, 59);">{</span><span> </span><span class="token token literal-property" style="color: rgb(184, 10, 24);">status</span><span class="token token" style="color: rgb(20, 24, 31);">:</span><span> </span><span class="token token" style="color: rgb(0, 128, 0);">"unsupported"</span><span class="token token" style="color: rgb(43, 48, 59);">,</span><span> </span><span class="token token literal-property" style="color: rgb(184, 10, 24);">reason</span><span class="token token" style="color: rgb(20, 24, 31);">:</span><span> </span><span class="token token" style="color: rgb(0, 128, 0);">"hardware_virt_disabled"</span><span> </span><span class="token token" style="color: rgb(43, 48, 59);">}</span><span>
</span></span><span><span></span><span class="token token" style="color: rgb(43, 48, 59);">}</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]">vs()</code> function calls into the native <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]">CoworkVMService</code> binary (<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]">cowork-svc.exe</code>). 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]">isHardwareVirtEnabled()</code> check appears to return <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]">false</code> on this system despite all virtualization features being properly enabled and verified.</p>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]"><strong>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]">reason</code> field is not logged anywhere</strong>, making it impossible to confirm from logs alone which check fails. The only log output is:</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="클립보드에 복사" 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>yukonSilver not supported (status=unsupported), checking for stale bundle...
</span></span><span>[startVM] VM not supported (win32/x64), skipping</span></code></pre></div></div>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Comparison: Working PC vs Broken PC</h2>
<div class="overflow-x-auto w-full px-2 mb-6">
Property | Working PC (i3-12100) | Broken PC (i5-14600K)
-- | -- | --
OS | Win 11 Pro 25H2 Build 26200 | Win 11 Pro 25H2 Build 26200
Claude Version | 1.1.3918.0 | 1.1.3918.0
cowork-svc.exe MD5 | 27EBA83BBE4D8457D738B36863E1EFB4 | 27EBA83BBE4D8457D738B36863E1EFB4
GrowthBook features | 27 | 27
CoworkVMService | Running / Automatic | Running / Automatic
Secure Boot | True | True (was False, fixed during debugging)
VirtualMachinePlatform | Enabled | Enabled
Microsoft-Hyper-V-All | Disabled | Tested both Enabled and Disabled
HypervisorPlatform | Disabled | Tested both Enabled and Disabled
vmcompute.exe | Exists | Exists
vm_bundles directory | Present (with full VM files) | Missing (never created)
VM log | [startVM] VM already connected | [startVM] VM not supported (win32/x64), skipping
vmcompute service | Running | Running
vmms service | Running | Running
RAM | - | 64 GB
HNS Network | - | cowork-vm-vnet exists (ICS type)
NetNat | - | Empty (no NAT rule)

</div>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Configurations Tested (All Failed)</h2>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">The following configurations were all tested on the broken PC with full reboots between each:</p>
<ol class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&: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">✅ BIOS: Intel VMX Virtualization Technology = Enabled</li>
<li class="whitespace-normal break-words pl-2">✅ BIOS: Secure Boot = Enabled (was disabled, fixed by restoring factory keys)</li>
<li class="whitespace-normal break-words pl-2">✅ BIOS: CSM = Disabled</li>
<li class="whitespace-normal break-words pl-2">❌ Hyper-V All enabled + VirtualMachinePlatform + HypervisorPlatform → unsupported</li>
<li class="whitespace-normal break-words pl-2">❌ Hyper-V All disabled + VirtualMachinePlatform only (matching working PC) → unsupported</li>
<li class="whitespace-normal break-words pl-2">❌ Hyper-V All disabled + VirtualMachinePlatform + HypervisorPlatform → unsupported</li>
<li class="whitespace-normal break-words pl-2">❌ Hyper-V All disabled + HypervisorPlatform disabled + VirtualMachinePlatform only → unsupported</li>
<li class="whitespace-normal break-words pl-2">❌ Full cache clear (Local Storage, Session Storage, logs, GPUCache, Code Cache) → unsupported</li>
<li class="whitespace-normal break-words pl-2">❌ CoworkVMService restart + Claude restart → unsupported</li>
</ol>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Cowork VM Log (representative sample)</h2>
<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="클립보드에 복사" 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>2026-02-21 16:52:51 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
</span></span><span>2026-02-21 16:52:54 [warn] [startVM] VM not supported (win32/x64), skipping
</span><span>2026-02-21 16:52:54 [info] [Callbacks] Initializing VM event callbacks...
</span><span>2026-02-21 16:52:54 [info] [VM] Loading vmClient (TypeScript) module...
</span><span>2026-02-21 16:52:54 [info] [VM] Module loaded successfully
</span><span>2026-02-21 16:52:54 [info] [Callbacks] VM event callbacks initialized
</span><span>2026-02-21 16:52:55 [warn] [startVM] VM not supported (win32/x64), skipping</span></code></pre></div></div>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Main Log (relevant excerpt)</h2>
<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="클립보드에 복사" 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>2026-02-21 16:52:50 [info] Starting app {
</span></span><span> appVersion: '1.1.3918',
</span><span> platform: 'win32',
</span><span> arch: 'x64',
</span><span> nodeVersion: '24.13.0'
</span><span>}
</span><span>2026-02-21 16:52:50 [info] [MSIX] Package family from native API: Claude_pzs8sxrjxfjjc
</span><span>2026-02-21 16:52:50 [info] [updater] MSIX detected: windowsStore=true, appPathMatch=true, source=windowsStore
</span><span>2026-02-21 16:52:51 [info] [growthbook] loaded 27 features (27 changed)
</span><span>2026-02-21 16:52:53 [info] [VMCLIRunner] Ensuring VM is started</span></code></pre></div></div>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Elevation status from event logging:</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="클립보드에 복사" 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>elevation_type: 'limited',
</span></span><span>can_elevate: true</span></code></pre></div></div>
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</html>

What Should Happen?

With all virtualization features enabled (VirtualMachinePlatform, Secure Boot, Intel VT-x), the yukonSilver VM configuration should be classified as "supported" and the Cowork workspace should start normally. The same account and Claude Desktop version (1.1.3918.0) works correctly on another PC (i3-12100, same OS build 26200).

Error Messages/Logs

From cowork_vm_node.log:
[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
[startVM] VM not supported (win32/x64), skipping

UI error: "가상화가 활성화되지 않았습니다" (Virtualization is not enabled)
MCP server connection failures: mcp-registry, Claude in Chrome

The vm_bundles directory is never created — the VM never attempts to boot.

Steps to Reproduce

Windows 11 Pro x64, Build 26200, Intel i5-14600K, 64GB RAM
BIOS: Intel VMX enabled, Secure Boot enabled, CSM disabled
Windows: VirtualMachinePlatform enabled, vmcompute and vmms services running
Install Claude Desktop v1.1.3918.0 from claude.ai/download
Open Cowork tab
Error: "Virtualization is not enabled"
Tested all combinations of Hyper-V/HypervisorPlatform enabled/disabled — all fail

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Desktop v1.1.3918.0 (MSIX)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_

View original on GitHub ↗

5 Comments

github-actions[bot] · 6 months ago

Found 2 possible duplicate issues:

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

typhoon1707 · 6 months ago

This is not a duplicate.

#27354 and #27323 may describe similar symptoms, but this issue provides unique diagnostic value:

Source code analysis — I traced the exact code path: EPt() → vs().isHardwareVirtEnabled() returns false despite all virtualization being enabled
Side-by-side comparison with a working PC (same account, same Claude version 1.1.3918.0, same OS build 26200) — confirming the issue is hardware-specific, not account/version related
Exhaustive elimination — tested all 7+ combinations of Hyper-V/VMP/HypervisorPlatform/SecureBoot configurations, all fail
The reason field from EPt() is never logged — this is a concrete improvement suggestion that would help triage all related issues

The root cause appears to be in the native cowork-svc.exe binary's isHardwareVirtEnabled() check, which is not diagnosable from logs alone.

jamespitarresi · 6 months ago

Same issue — Dell Precision 7920 Tower, Intel Xeon Gold 6226R, 64GB RAM, Windows 11 Pro for Workstations, Build 26200.
Log confirms identical errors:

yukonSilver not supported (status=unsupported)
VM not supported (win32/x64), skipping
Swift VM addon not available for callbacks

Hyper-V is enabled, virtualization is confirmed active in Task Manager and msinfo32 ("A hypervisor has been detected"). All Windows features enabled. Fresh install of latest Claude Desktop made no difference. This has been happening since January 24th per my logs.

MarshallOfSound · 6 months ago

Closing as duplicate of #27316 which was very rapidly fixed in the v1.1.3963 release