›_ Claude Code Issues
Claude Code Issues / #38373

**[BUG] Cowork shows "VM not supported (win32/x64)" — yukonSilver unsupported on Intel 4th Gen CPU**

Resolved 💬 3 comments Opened Mar 24, 2026 by Davidfreedolia Closed Mar 27, 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?

[BUG] Cowork shows "VM not supported (win32/x64)" — yukonSilver unsupported on Intel 4th Gen CPU

---

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: latest version (app-1.1.799+)
  • OS: Windows 11 x64
  • CPU: Intel Core i7-4900MQ @ 2.80GHz (4th Gen, 4 cores / 8 logical processors)
  • Subscription: Pro
  • Virtualization: Enabled (confirmed in Task Manager)
  • Virtual Machine Platform: Enabled
  • Hyper-V: Enabled

---

What's Wrong?

The Cowork tab never initializes the VM. The logs show two recurring issues:

  1. yukonSilver not supported (status=unsupported) — present since January 2026
  2. VM not supported (win32/x64), skipping — appears from February 25, 2026 onward

The second error appears to be a platform-level exclusion for Windows x64, which may be related to the CPU generation (Intel 4th Gen, 2013). This is different from other reported issues where yukonSilver alone was the cause.

---

Steps to Reproduce

  1. Install Claude Desktop on Windows 11 x64 with Intel i7-4900MQ
  2. Enable Virtual Machine Platform, Hyper-V, and Windows Hypervisor Platform
  3. Open Claude Desktop → Cowork tab
  4. Observe that VM never starts
  5. Check %APPDATA%\Claude\logs\cowork_vm_node.log → repeated VM not supported (win32/x64), skipping

---

Relevant log excerpts

2026-02-25 12:08:33 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-25 12:08:33 [error] [Callbacks] Swift VM addon not available for callbacks
2026-03-05 21:07:43 [warn] [startVM] VM not supported (win32/x64), skipping
2026-03-24 12:23:50 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)

---

Expected Behavior
Cowork should either work on Windows x64 with a supported CPU, or surface a clear and specific error message indicating the minimum hardware requirements.

Actual Behavior
Cowork silently skips VM initialization with a generic VM not supported (win32/x64) warning, with no user-facing explanation.

---

Related issues: #32004, #27316, #27420, #29887, #36365

What Should Happen?

[BUG] Cowork shows "VM not supported (win32/x64)" — yukonSilver unsupported on Intel 4th Gen CPU

---

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: latest version (app-1.1.799+)
  • OS: Windows 11 x64
  • CPU: Intel Core i7-4900MQ @ 2.80GHz (4th Gen, 4 cores / 8 logical processors)
  • Subscription: Pro
  • Virtualization: Enabled (confirmed in Task Manager)
  • Virtual Machine Platform: Enabled
  • Hyper-V: Enabled

---

What's Wrong?

The Cowork tab never initializes the VM. The logs show two recurring issues:

  1. yukonSilver not supported (status=unsupported) — present since January 2026
  2. VM not supported (win32/x64), skipping — appears from February 25, 2026 onward

The second error appears to be a platform-level exclusion for Windows x64, which may be related to the CPU generation (Intel 4th Gen, 2013). This is different from other reported issues where yukonSilver alone was the cause.

---

Steps to Reproduce

  1. Install Claude Desktop on Windows 11 x64 with Intel i7-4900MQ
  2. Enable Virtual Machine Platform, Hyper-V, and Windows Hypervisor Platform
  3. Open Claude Desktop → Cowork tab
  4. Observe that VM never starts
  5. Check %APPDATA%\Claude\logs\cowork_vm_node.log → repeated VM not supported (win32/x64), skipping

---

Relevant log excerpts

2026-02-25 12:08:33 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-25 12:08:33 [error] [Callbacks] Swift VM addon not available for callbacks
2026-03-05 21:07:43 [warn] [startVM] VM not supported (win32/x64), skipping
2026-03-24 12:23:50 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)

---

Expected Behavior
Cowork should either work on Windows x64 with a supported CPU, or surface a clear and specific error message indicating the minimum hardware requirements.

Actual Behavior
Cowork silently skips VM initialization with a generic VM not supported (win32/x64) warning, with no user-facing explanation.

---

Related issues: #32004, #27316, #27420, #29887, #36365

Error Messages/Logs

**[BUG] Cowork shows "VM not supported (win32/x64)" — yukonSilver unsupported on Intel 4th Gen CPU**

---

**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: latest version (app-1.1.799+)
- OS: Windows 11 x64
- CPU: Intel Core i7-4900MQ @ 2.80GHz (4th Gen, 4 cores / 8 logical processors)
- Subscription: Pro
- Virtualization: Enabled (confirmed in Task Manager)
- Virtual Machine Platform: Enabled
- Hyper-V: Enabled

---

**What's Wrong?**

The Cowork tab never initializes the VM. The logs show two recurring issues:

1. `yukonSilver not supported (status=unsupported)` — present since January 2026
2. `VM not supported (win32/x64), skipping` — appears from February 25, 2026 onward

The second error appears to be a platform-level exclusion for Windows x64, which may be related to the CPU generation (Intel 4th Gen, 2013). This is different from other reported issues where yukonSilver alone was the cause.

---

**Steps to Reproduce**
1. Install Claude Desktop on Windows 11 x64 with Intel i7-4900MQ
2. Enable Virtual Machine Platform, Hyper-V, and Windows Hypervisor Platform
3. Open Claude Desktop → Cowork tab
4. Observe that VM never starts
5. Check `%APPDATA%\Claude\logs\cowork_vm_node.log` → repeated `VM not supported (win32/x64), skipping`

---

**Relevant log excerpts**


2026-02-25 12:08:33 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-25 12:08:33 [error] [Callbacks] Swift VM addon not available for callbacks
2026-03-05 21:07:43 [warn] [startVM] VM not supported (win32/x64), skipping
2026-03-24 12:23:50 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)


---

**Expected Behavior**
Cowork should either work on Windows x64 with a supported CPU, or surface a clear and specific error message indicating the minimum hardware requirements.

**Actual Behavior**
Cowork silently skips VM initialization with a generic `VM not supported (win32/x64)` warning, with no user-facing explanation.

---

**Related issues:** #32004, #27316, #27420, #29887, #36365

Steps to Reproduce

[BUG] Cowork shows "VM not supported (win32/x64)" — yukonSilver unsupported on Intel 4th Gen CPU

---

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: latest version (app-1.1.799+)
  • OS: Windows 11 x64
  • CPU: Intel Core i7-4900MQ @ 2.80GHz (4th Gen, 4 cores / 8 logical processors)
  • Subscription: Pro
  • Virtualization: Enabled (confirmed in Task Manager)
  • Virtual Machine Platform: Enabled
  • Hyper-V: Enabled

---

What's Wrong?

The Cowork tab never initializes the VM. The logs show two recurring issues:

  1. yukonSilver not supported (status=unsupported) — present since January 2026
  2. VM not supported (win32/x64), skipping — appears from February 25, 2026 onward

The second error appears to be a platform-level exclusion for Windows x64, which may be related to the CPU generation (Intel 4th Gen, 2013). This is different from other reported issues where yukonSilver alone was the cause.

---

Steps to Reproduce

  1. Install Claude Desktop on Windows 11 x64 with Intel i7-4900MQ
  2. Enable Virtual Machine Platform, Hyper-V, and Windows Hypervisor Platform
  3. Open Claude Desktop → Cowork tab
  4. Observe that VM never starts
  5. Check %APPDATA%\Claude\logs\cowork_vm_node.log → repeated VM not supported (win32/x64), skipping

---

Relevant log excerpts

2026-02-25 12:08:33 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-25 12:08:33 [error] [Callbacks] Swift VM addon not available for callbacks
2026-03-05 21:07:43 [warn] [startVM] VM not supported (win32/x64), skipping
2026-03-24 12:23:50 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)

---

Expected Behavior
Cowork should either work on Windows x64 with a supported CPU, or surface a clear and specific error message indicating the minimum hardware requirements.

Actual Behavior
Cowork silently skips VM initialization with a generic VM not supported (win32/x64) warning, with no user-facing explanation.

---

Related issues: #32004, #27316, #27420, #29887, #36365

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

sonnet 4.6

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_

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