[BUG] Processor not supported

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?

This is very revealing. The sequence in the logs is:

✅ 2:51:38 — VM started successfully
✅ 2:51:39 — Guest OS powered on the virtual PCI device (Linux kernel booted)
❌ 2:51:46 — Guest OS powered off the PCI device and VM shut down

The Linux kernel inside the VM is actually booting, but then immediately panicking and shutting itself down within 7 seconds. This is a guest kernel crash — not a Windows/Hyper-V problem. Everything on your side is working correctly.
This is almost certainly a bug with Cowork's Linux kernel image and your specific CPU configuration. Notice this line in the logs:
Guest processor features: 0x3E1FFBCFE7F7859F
Partition creation flags: 0x8080000000100

What Should Happen?

At this point, please file a bug at github.com/anthropics/claude-code/issues and attach:

The VMMS log output you just got
Your cowork_vm_node.log file
Your CPU model (run Get-WmiObject Win32_Processor | Select-Object Name)

This is exactly the kind of data Anthropic needs to fix the kernel crash. You've done everything right — the issue is in Cowork's Linux image, not your system.

Error Messages/Logs

>> # Also check Hyper-V-VMMS
>> Get-WinEvent -LogName "Microsoft-Windows-Hyper-V-VMMS-Admin" -MaxEvents 20 |
>>   Select-Object TimeCreated, Message | Format-List


TimeCreated : 3/19/2026 2:51:46 PM
Message     : 'cowork-vm' was turned off. (Virtual machine ID 960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:46 PM
Message     : 'cowork-vm': A virtual PCI device was successfully revoked from the virtual machine: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:46 PM
Message     : 'cowork-vm': The guest operating system powered off a virtual PCI device: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:39 PM
Message     : 'cowork-vm': The guest operating system powered on a virtual PCI device: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:39 PM
Message     : 'cowork-vm': Virtual machine successfully negotiated Virtual PCI protocol version 0x10004 on 'Channel
              {C4B741F5-5582-4C98-8F8B-2E082933C396} [VTL0]'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:38 PM
Message     : 'cowork-vm' The -FC59-5B4B-843D-68737D617893 repository has logged performance summary (Virtual
              machine ID {00360039-0030-0045-3100-310030004300}) [runtime]: Finished starting the VM's VMWP

TimeCreated : 3/19/2026 2:51:38 PM
Message     : 'cowork-vm' The -FC59-5B4B-843D-68737D617893 repository has logged performance summary (Virtual
              machine ID {00360039-0030-0045-3100-310030004300}) [configuration]: Finished starting the VM's VMWP

TimeCreated : 3/19/2026 2:51:38 PM
Message     : 'cowork-vm' started successfully. (Virtual machine ID 960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:38 PM
Message     : 'cowork-vm':  (1FF46D3F-E712-5DBC-9813-AAD51981A2E9) started successfully. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:37 PM
Message     : 'cowork-vm': A virtual PCI device was successfully offered to the virtual machine: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. PnpID =
              'PCI\VEN_1AF4&DEV_1043&SUBSYS_00401AF4&REV_01', FunctionType = FlexIO. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:51:37 PM
Message     : 'cowork-vm' The -FC59-5B4B-843D-68737D617893 repository has logged performance summary (Virtual
              machine ID {00360039-0030-0045-3100-310030004300}) [runtime]: Completed
              VirtualMachine::InitializeInternal

TimeCreated : 3/19/2026 2:51:37 PM
Message     : 'cowork-vm' The -FC59-5B4B-843D-68737D617893 repository has logged performance summary (Virtual
              machine ID {00360039-0030-0045-3100-310030004300}) [configuration]: Completed
              VirtualMachine::InitializeInternal

TimeCreated : 3/19/2026 2:51:37 PM
Message     : 'cowork-vm' properties were successfully initialized. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)
              Guest processor features: 0x3E1FFBCFE7F7859F, 0x111800E177382
              Guest xsave features: 0x3C058381F
              Partition creation flags: 0x8080000000100
              Non architectural core sharing: 1
              Cache line flush size: 8
              Address bit width: 46
              Physical address width: 46

TimeCreated : 3/19/2026 2:18:03 PM
Message     : 'cowork-vm' was turned off. (Virtual machine ID 960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:18:03 PM
Message     : 'cowork-vm': A virtual PCI device was successfully revoked from the virtual machine: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:18:03 PM
Message     : 'cowork-vm': The guest operating system powered off a virtual PCI device: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:18:00 PM
Message     : 'cowork-vm': The guest operating system powered on a virtual PCI device: 'Bus
              {C4B741F5-5582-4C98-8F8B-2E082933C396} Slot 0'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:18:00 PM
Message     : 'cowork-vm': Virtual machine successfully negotiated Virtual PCI protocol version 0x10004 on 'Channel
              {C4B741F5-5582-4C98-8F8B-2E082933C396} [VTL0]'. (Virtual machine ID
              960E110C-FC59-5B4B-843D-68737D617893)

TimeCreated : 3/19/2026 2:17:59 PM
Message     : 'cowork-vm' The -FC59-5B4B-843D-68737D617893 repository has logged performance summary (Virtual
              machine ID {00360039-0030-0045-3100-310030004300}) [runtime]: Finished starting the VM's VMWP

TimeCreated : 3/19/2026 2:17:59 PM
Message     : 'cowork-vm' The -FC59-5B4B-843D-68737D617893 repository has logged performance summary (Virtual
              machine ID {00360039-0030-0045-3100-310030004300}) [configuration]: Finished starting the VM's VMWP





TimeCreated : 3/19/2026 1:35:10 PM
Message     : The WMI provider 'VmmsWmiEventProvider' has started.

TimeCreated : 3/19/2026 1:35:10 PM
Message     : The WMI provider 'VmmsWmiInstanceAndMethodProvider' has started.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Virtual Machine Management service is started successfully.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Incremental Replication will timeout after 360 hours. Minimum value for timeout is 6 hours.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Hyper-V would age out CDP reference points after 720 hours.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Change tracking has defined following limits for pending log file size.
              Error limit : 50% (Minimum value 10%. Maximum value 100%).
              Warning limit : 40%.
              Information limit : 30%.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Change tracking has defined following limits for free disk space.
              Free Disk space error limit 3072 MBs (Minimum value can be 1024 MBs).
              Free Disk space warning limit 4915 MBs.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Successfully started the Virtual Machine migration connection manager.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : Found a certificate for server authentication. Remote access to virtual machines is now possible.

TimeCreated : 3/19/2026 1:35:09 PM
Message     : The Virtual Machine Management service has successfully waited for the servicing servicing operation
              to complete.

TimeCreated : 3/19/2026 1:35:05 PM
Message     : The Virtual Machine Management service is waiting for a servicing operation (servicing) to complete.

TimeCreated : 3/19/2026 1:34:30 PM
Message     : The WMI provider 'VmmsWmiInstanceAndMethodProvider' has shut down.

TimeCreated : 3/19/2026 1:34:30 PM
Message     : The WMI provider 'VmmsWmiEventProvider' has shut down.

TimeCreated : 3/19/2026 1:34:30 PM
Message     : Shut down physical computer. Stopping/saving all virtual machines...

TimeCreated : 3/19/2026 1:26:38 PM
Message     : The WMI provider 'VmmsWmiEventProvider' has started.

TimeCreated : 3/19/2026 1:26:38 PM
Message     : The WMI provider 'VmmsWmiInstanceAndMethodProvider' has started.

TimeCreated : 3/19/2026 1:26:38 PM
Message     : Virtual Machine Management service is started successfully.

TimeCreated : 3/19/2026 1:26:38 PM
Message     : Incremental Replication will timeout after 360 hours. Minimum value for timeout is 6 hours.

TimeCreated : 3/19/2026 1:26:38 PM
Message     : Hyper-V would age out CDP reference points after 720 hours.

TimeCreated : 3/19/2026 1:26:38 PM
Message     : Change tracking has defined following limits for pending log file size.
              Error limit : 50% (Minimum value 10%. Maximum value 100%).
              Warning limit : 40%.
              Information limit : 30%.



PS C:\Windows\system32>

Steps to Reproduce

cowork_vm_node.log

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

version 1.1.7464.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

PS C:\Windows\system32> Get-WmiObject Win32_Processor | Select-Object Name

Name
----
Intel(R) Core(TM) Ultra 9 285H