[BUG] Cowork fails to start continuously

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?

Cowork workspace fails to start: "VM service not running. The service failed to start."
The cowork-service.log shows the VM starts successfully and API is reachable, but claude.exe drops the RPC connection immediately with "Persistent RPC: connection ended: failed to read length: EOF".

What Should Happen?

Cowork workspace should start and remain connected.

Error Messages/Logs

Persistent RPC: connection ended: failed to read length: EOF
Session ... has no active connections, idle timeout starts

Steps to Reproduce

1. Open Claude Desktop
2. Navigate to Cowork
3. Observe error: "Failed to start Claude's workspace"
4. cowork-service.log shows VM starts but RPC connection drops immediately

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.1.9310.0

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

}
}
}
}
}
}
2026/03/28 22:32:15.329630 [VM] Creating HCS compute system...
2026/03/28 22:32:15.329630 [HCS] Calling HcsCreateComputeSystem with id=cowork-vm-b98b58b7
2026/03/28 22:32:15.329630 [HCS] Config JSON:
{"Owner":"cowork-vm-b98b58b7","SchemaVersion":{"Major":2,"Minor":2},"ShouldTerminateOnLastHandleClosed":true,"VirtualMachine":{"Chipset":{"LinuxKernelDirect":{"InitRdPath":"C:\\Users\\berti\\AppData\\Local\\Packages\\Claude_pzs8sxrjxfjjc\\LocalCache\\Roaming\\Claude\\vm_bundles\\claudevm.bundle\\initrd","KernelCmdLine":"console=ttyS0 earlyprintk=serial root=/dev/sda1 rootfstype=ext4 rw panic=10","KernelFilePath":"C:\\Users\\berti\\AppData\\Local\\Packages\\Claude_pzs8sxrjxfjjc\\LocalCache\\Roaming\\Claude\\vm_bundles\\claudevm.bundle\\vmlinuz"}},"ComputeTopology":{"Memory":{"AllowOvercommit":true,"SizeInMB":4096},"Processor":{"Count":2}},"Devices":{"HvSocket":{"HvSocketConfig":{"DefaultBindSecurityDescriptor":"D:P(A;;FA;;;WD)","DefaultConnectSecurityDescriptor":"D:P(A;;FA;;;WD)","ServiceTable":{"00000400-facb-11e6-bd58-64006a7986d3":{"AllowWildcardBinds":true,"BindSecurityDescriptor":"D:P(A;;FA;;;WD)","ConnectSecurityDescriptor":"D:P(A;;FA;;;WD)"},"0000c822-facb-11e6-bd58-64006a7986d3":{"AllowWildcardBinds":true,"BindSecurityDescriptor":"D:P(A;;FA;;;WD)","ConnectSecurityDescriptor":"D:P(A;;FA;;;WD)"}}}},"Plan9":{},"Scsi":{"Primary SCSI Controller":{"Attachments":{"0":{"Path":"C:\\Users\\berti\\AppData\\Local\\Packages\\Claude_pzs8sxrjxfjjc\\LocalCache\\Roaming\\Claude\\vm_bundles\\claudevm.bundle\\rootfs.vhdx","Type":"VirtualDisk"},"1":{"Path":"C:\\Users\\berti\\AppData\\Local\\Packages\\Claude_pzs8sxrjxfjjc\\LocalCache\\Roaming\\Claude\\vm_bundles\\claudevm.bundle\\smol-bin.vhdx","ReadOnly":true,"Type":"VirtualDisk"},"2":{"Path":"C:\\Users\\berti\\AppData\\Local\\Packages\\Claude_pzs8sxrjxfjjc\\LocalCache\\Roaming\\Claude\\vm_bundles\\claudevm.bundle\\sessiondata.vhdx","Type":"VirtualDisk"}}}},"VirtioSerial":{"Ports":{"0":{"Name":"claude-daemon-console","NamedPipe":"\\\\.\\pipe\\cowork-daemon-console-cowork-vm-b98b58b7"}}}}}}
2026/03/28 22:32:15.329630 [HCS] Created operation handle: 1558839468016
2026/03/28 22:32:15.332473 [HCS] HcsCreateComputeSystem returned: hr=0x0, handle=1558839464400, lastErr=The operation completed successfully.
2026/03/28 22:32:15.868342 [HCS] HcsWaitForOperationResult returned: hr=0x0
2026/03/28 22:32:15.868722 [HCS] Result JSON: (nil)
2026/03/28 22:32:15.868722 [HCS] HcsGetComputeSystemProperties returned: hr=0x0
2026/03/28 22:32:15.869229 [HCS] Properties result: {"Id":"cowork-vm-b98b58b7","SystemType":"VirtualMachine","Owner":"cowork-vm-b98b58b7","RuntimeId":"a764f6e1-cd46-5816-ad85-98f06e981ae8"}
2026/03/28 22:32:15.869229 [VM] Got VM runtime ID: a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:15.869229 [VM] Starting RPC server for vsock connections...
2026/03/28 22:32:15.869229 [HVSock] Creating listener:
2026/03/28 22:32:15.869229 [HVSock] VMID: a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:15.869229 [HVSock] Port: 51234 (0xc822)
2026/03/28 22:32:15.869229 [HVSock] ServiceGUID: 0000c822-facb-11e6-bd58-64006a7986d3
2026/03/28 22:32:15.882618 [HVSock] Listening on port 51234 (service GUID: 0000c822-facb-11e6-bd58-64006a7986d3)
2026/03/28 22:32:15.882618 [RPC] Server started, waiting for sdk-daemon connection on port 51234
2026/03/28 22:32:15.882618 [HVSock] Creating listener:
2026/03/28 22:32:15.882618 [HVSock] VMID: a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:15.882618 [HVSock] Port: 1024 (0x400)
2026/03/28 22:32:15.882618 [HVSock] ServiceGUID: 00000400-facb-11e6-bd58-64006a7986d3
2026/03/28 22:32:15.882618 [HVSock] Listening on port 1024 (service GUID: 00000400-facb-11e6-bd58-64006a7986d3)
2026/03/28 22:32:15.882618 [VNet] Listening for VM network connections on vsock port 1024
2026/03/28 22:32:15.993783 [VM] Granted VM access to: C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx for NT VIRTUAL MACHINE\a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:16.061641 [VM] Granted VM access to: C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\vmlinuz for NT VIRTUAL MACHINE\a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:16.134660 [VM] Granted VM access to: C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\initrd for NT VIRTUAL MACHINE\a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:16.212596 [VM] Granted VM access to: C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx for NT VIRTUAL MACHINE\a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:16.304588 [VM] Granted VM access to: C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\sessiondata.vhdx for NT VIRTUAL MACHINE\a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:16.305233 [VM] Starting compute system...
2026/03/28 22:32:16.305233 [HCS] HcsStartComputeSystem returned: hr=0x0, lastErr=The operation completed successfully.
2026/03/28 22:32:16.847321 [VM] Adding Plan9 share via HcsModifyComputeSystem: name=home path=C:\Users\berti port=9999 flags=0x10 hasToken=true
2026/03/28 22:32:16.847879 [HCS] Calling HcsModifyComputeSystem
2026/03/28 22:32:16.847879 [HCS] Config: {"ResourcePath":"VirtualMachine/Devices/Plan9/Shares","RequestType":"Add","Settings":{"Name":"home","AccessName":"home","Path":"C:\\Users\\berti","Port":9999,"Flags":16}}
2026/03/28 22:32:16.847879 [HCS] HcsModifyComputeSystem returned: hr=0x0, lastErr=The operation completed successfully.
2026/03/28 22:32:16.899491 [VM] Starting daemon console reader: pipe=\\.\pipe\cowork-daemon-console-cowork-vm-b98b58b7 log=C:\ProgramData\Claude\Logs\coworkd\user-S-1-5-21-3119812603-2117476835-2796231555-1001.log
2026/03/28 22:32:16.899491 [VM] VM started successfully
2026/03/28 22:32:16.903150 [Console] Connected to daemon console pipe: \\.\pipe\cowork-daemon-console-cowork-vm-b98b58b7
2026/03/28 22:32:24.841515 [HVSock] Accepted connection from VM=a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:24.841515 [VNet] VM network connected from a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:29.399500 [HVSock] Accepted connection from VM=a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:29.399500 [RPC] sdk-daemon connected from VM a764f6e1-cd46-5816-ad85-98f06e981ae8
2026/03/28 22:32:29.400073 [RPC] Network status: CONNECTED
2026/03/28 22:32:29.400073 [VM] Network status: CONNECTED
2026/03/28 22:32:29.400073 [RPC] sdk-daemon is ready
2026/03/28 22:32:29.400073 [VM] sdk-daemon is ready!
2026/03/28 22:32:29.414778 [Certs] Loaded 89 CA certificates from Windows ROOT store
2026/03/28 22:32:29.415366 [RPC] Sending 89 CA certificates for installation
2026/03/28 22:32:29.628787 [RPC] API reachability: REACHABLE
2026/03/28 22:32:29.628787 [VM] API reachability: REACHABLE
2026/03/28 22:32:33.396814 [VM] Installed 89 CA certificates in guest
2026/03/28 22:32:44.336182 [RPC] Process a18cf136-0c88-4c39-ba5d-a655693eb833 exited: code=0xc00000bb08 signal=<nil>
2026/03/28 22:32:44.336725 [VM] exit[a18cf136-0c88-4c39-ba5d-a655693eb833]: code=0xc00000bb08 signal=<nil>
2026/03/28 22:35:19.780288 [RPC] Process 1eb01b27-dccd-4491-899c-5905cd784b25 exited: code=0xc00000b008 signal=<nil>
2026/03/28 22:35:19.780288 [VM] exit[1eb01b27-dccd-4491-899c-5905cd784b25]: code=0xc00000b008 signal=<nil>
2026/03/28 22:36:34.126275 [RPC] Process 0a04a55a-2564-4f17-b34d-c72dbeca241d exited: code=0xc00077e218 signal=<nil>
2026/03/28 22:36:34.126275 [VM] exit[0a04a55a-2564-4f17-b34d-c72dbeca241d]: code=0xc00077e218 signal=<nil>
2026/03/28 22:38:37.494872 [RPC] Process f0c4208f-b340-4a03-a7f9-085a233d0c25 exited: code=0xc000589730 signal=<nil>
2026/03/28 22:38:37.494872 [VM] exit[f0c4208f-b340-4a03-a7f9-085a233d0c25]: code=0xc000589730 signal=<nil>
2026/03/28 22:39:47.546649 [RPC] Process 3cff69bf-c36e-4dbd-b939-b415e01ed7c7 exited: code=0xc000c87f50 signal=<nil>
2026/03/28 22:39:47.546649 [VM] exit[3cff69bf-c36e-4dbd-b939-b415e01ed7c7]: code=0xc000c87f50 signal=<nil>
2026/03/28 22:40:57.878580 [RPC] Process 03051be6-0cb0-4b0b-acb9-7210f2123835 exited: code=0xc000616770 signal=<nil>
2026/03/28 22:40:57.879385 [VM] exit[03051be6-0cb0-4b0b-acb9-7210f2123835]: code=0xc000616770 signal=<nil>
2026/03/28 22:54:10.214654 Starting CoworkVMService as Windows service
2026/03/28 22:54:10.217898 Claude VM Service starting...
2026/03/28 22:54:10.217898 Waiting for configuration from app via 'configure' method...
2026/03/28 22:54:10.217898 [HCS] Initializing HCS DLLs...
2026/03/28 22:54:10.218498 Warning: failed to open service for recovery config: Access is denied.
2026/03/28 22:54:10.252234 [HCS] vmcompute.dll loaded successfully
2026/03/28 22:54:10.278586 [HCS] computecore.dll loaded successfully
2026/03/28 22:54:10.278586 [HCS] Procs initialized, HCS ready
2026/03/28 22:54:10.278586 [HCN] Initialized HCN API from computenetwork.dll
2026/03/28 22:54:10.285865 [HCN] EnumerateNetworks result: ["c08cb7b8-9b3c-408e-8e30-5e16a3aeb444"]
2026/03/28 22:54:10.412514 [Server] Signature verification initialized
2026/03/28 22:54:10.412514 [Server] Service: C:\Program Files\WindowsApps\Claude_1.1.9310.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe
2026/03/28 22:54:10.412514 [Server] Subject: Anthropic, PBC
2026/03/28 22:54:10.412514 [Server] Thumbprint: dbde5d16768ed0c1...
2026/03/28 22:54:10.412514 [Server] Enforce: true
2026/03/28 22:54:10.412514 [Server] Starting named pipe server on \\.\pipe\cowork-vm-service
2026/03/28 22:54:10.413020 [Server] Named pipe server listening
2026/03/28 22:54:10.413020 Service ready. Listening on \\.\pipe\cowork-vm-service
2026/03/28 22:54:10.441974 [Server] Client connected
2026/03/28 22:54:10.444102 [VM] VM owner set: id=cowork-vm-b98b58b7 sid=S-1-5-21-3119812603-2117476835-2796231555-1001
2026/03/28 22:54:10.444102 [VM] Event callbacks set
2026/03/28 22:54:10.444102 [Server] Created new VM session for berti:C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
2026/03/28 22:54:10.444102 [Server] Event subscriber connected for berti:C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude (total: 1)
2026/03/28 22:54:11.211347 [Server] Client connected
2026/03/28 22:54:11.856681 [Server] Client signature verified: C:\Program Files\WindowsApps\Claude_1.1.9310.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/03/28 22:54:11.857223 [Server] Persistent RPC: entering loop
2026/03/28 22:54:11.917258 [Server] Persistent RPC: connection ended: failed to read length: EOF
2026/03/28 22:54:11.917258 [Server] Session berti:C:\Users\berti\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/03/28 22:55:07.170440 [Server] Client connected
2026/03/28 22:55:07.814432 [Server] Client signature verified: C:\Program Files\WindowsApps\Claude_1.1.9310.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/03/28 22:55:07.815474 [Server] Persistent RPC: entering loop