[BUG] yukonSilver VM flagged as "unsupported" on Windows 11 Pro Build 26200 despite all requirements met - GrowthBook feature flag issue (still unresolved)

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?

aThe Cowork VM (yukonSilver) is flagged as "unsupported" on my Windows 11 Pro x64 machine (Build 26200) despite meeting all system requirements. All virtualization features (Hyper-V, Virtual Machine Platform) are enabled and verified via PowerShell.

This is a known, recurring issue caused by the GrowthBook feature flag incorrectly marking certain machines as unsupported. It has been reported in multiple issues (#25136, #25142, #25505, #29322, #32004, #34201) over the past several months. Issues keep getting closed as "duplicate" but the root cause has never been fixed.

Key observations:

• Issue #25505 reported that yukonSilver went from "unsupported" to working without any user action, suggesting the flag is toggled server-side via GrowthBook in waves.
• - Issue #29322 identified that #25136 was closed after a different user with a different root cause reported a fix, but the original build detection bug was never actually resolved.
• - - As recently as March 13, 2026 (Issue #34201), users are still reporting this exact same problem on the latest version (1.1.6679).
• - - - Another machine in the same office with the same Pro account runs Cowork fine, confirming it's not an account or network issue.

I have tried updating through multiple versions (v1.1.3189 → v1.1.3541 → v1.1.3770 → v1.1.3830 → latest) with no change. I have also contacted Anthropic support multiple times (starting February 19) with no response.

This appears to be a server-side GrowthBook configuration issue that needs to be addressed by the engineering team responsible for feature flag rollouts.

What Should Happen?

aThe Cowork VM (yukonSilver) should be correctly detected as "supported" on Windows 11 Pro x64 Build 26200 with Hyper-V and Virtual Machine Platform enabled. The GrowthBook feature flag should not incorrectly block machines that meet all documented system requirements. Cowork should initialize and run the VM successfully, allowing Claude Code to function as intended for Max plan subscribers.

Error Messages/Logs

yukonSilver VM configuration marked as "unsupported"
GrowthBook feature flag blocks Cowork initialization
CoworkVMService cannot be removed even with Administrator privileges
Logs show: VM configuration "yukonSilver" is unsupported on this system

Steps to Reproduce

a1. Install Claude Desktop latest version (1.1.6679 or later) on Windows 11 Pro x64 Build 26200

1. Ensure Hyper-V and Virtual Machine Platform are enabled (verified via Get-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform)
2. 3. Open Claude Desktop and navigate to the Cowork tab
3. 4. Cowork shows "unsupported" status for the yukonSilver VM configuration
4. 5. The GrowthBook feature flag blocks initialization despite all system requirements being met
5. 6. Uninstalling and reinstalling does not resolve the issue
6. 7. Updating through multiple versions does not resolve the issue
7. 8. The CoworkVMService cannot be removed even with Administrator privileges

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.1.6679 (Claude Desktop with Cowork)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Related Issues (all describing the same root cause):

• #25136 - Original yukonSilver unsupported report (closed prematurely)
• - #25142 - Related yukonSilver detection issue
• - - #25505 - yukonSilver fixed itself without user action (server-side flag change)
• - - - #29322 - Identified that #25136 was closed incorrectly
• - - - - #32004 - Same issue on Windows 11 Pro Build 26200 (March 8, 2026)
• - - - - - #34201 - Same issue on Windows 10 Pro with Hyper-V (March 13, 2026)

Support tickets filed:

• Anthropic support ticket opened February 19, 2026 - no response received
• - Intercom support conversation ID: 215473497115812 (March 16, 2026)

Additional context:

• Another machine in the same office with the same Pro account runs Cowork without issues, confirming this is not an account-level or network-level problem
• - The issue appears to be related to GrowthBook feature flag rollout targeting, where certain machine configurations are incorrectly excluded
• - - Max plan subscriber paying for Claude Code access that has been unusable for over a month

I am requesting that this issue NOT be closed as "duplicate" without the root cause actually being fixed. Previous issues were closed prematurely and the bug persists.