Summary
Claude Desktop on Windows fails to enable Cowork with the message "Cowork requires a newer installation — Reinstall the desktop app." The "Reinstall" button does nothing. The root cause is a broken Squirrel-to-MSIX migration path that silently leaves the MSIX package in a non-virtualized state.
Plans affected: Claude Max Plan + Codex Enterprise
OS: Windows 11 Home 10.0.26200 Build 26200
Package: Claude_1.1.9134.0_x64__pzs8sxrjxfjjc (SignatureKind: Developer)
Root Cause (fully diagnosed with log evidence)
The app checks for MSIX filesystem virtualization at:
C:\Users\<user>\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
When this path doesn't exist, the app logs:
[MSIX] Filesystem not virtualized — path absent (likely Squirrel upgrade)
[warm] Skipping VM warm download - YukonSilver not supported (Cowork requires Claude Desktop be installed with our modern installer)
The yukonSilver feature is marked status=unsupported, which triggers TWO destructive behaviors:
- The "Cowork requires a newer installation" banner is shown
- The app actively deletes VM bundle files via
cleanupVMBundleIfUnsupported
The irony: Cowork VM works perfectly
The service log proves the VM runs fine on this machine:
[HCS] HcsCreateComputeSystem returned: hr=0x0 (VM created successfully)[VM] VM started successfully[RPC] sdk-daemon is ready[RPC] API reachability: REACHABLE- Dozens of Cowork processes ran successfully (10:29 AM - 3:30 PM on 2026-03-27)
The VM ran, processes completed, API was reachable — then on restart, the app checked the MSIX path, found it missing, declared Cowork unsupported, and deleted reinstall files.
Self-destructive deletion loop
The app repeatedly deletes VM bundle reinstall files every time it starts:
2026-03-26 19:14:19 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 21:18:43 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 21:55:45 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 22:02:59 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 22:05:50 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 22:52:28 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 22:58:49 [info] [deleteVMBundle] Deleting reinstall files
2026-03-26 23:18:23 [info] [deleteVMBundle] Deleting reinstall files
2026-03-27 16:33:28 [info] [deleteVMBundle] Deleting reinstall files
2026-03-27 17:35:07 [info] [deleteVMBundle] Deleting reinstall files
Environment
- CoworkVMService: Installed, starts/stops correctly (Automatic start type)
- HCS/vmcompute: Available and functional (Running)
- HvHost: Running
- WSL2: Installed with Docker Desktop
- MSIX
LocalCache\Roaming directory exists but has no Claude subfolder
- Hypervisor detected per systeminfo
- Virtualization-based security: Running
What needs to be fixed
- The Squirrel-to-MSIX migration must create the virtualized filesystem path. This is the root cause.
- Stop deleting VM bundle files when yukonSilver is "unsupported." The VM works — destroying the user's 10GB download based on a path check is hostile.
- Make the Reinstall button work. Or remove it and provide clear instructions.
- Provide a migration tool that preserves MCP configs, extensions, plugins, and the VM bundle.
- Test upgrade paths on Windows 11 Home — the most common consumer edition.
Impact
Real monetary loss across Claude Max Plan and Codex Enterprise. Hours of productive time lost diagnosing what turned out to be a missing directory in a broken migration path. 8 daily scheduled tasks for a consulting business were disrupted.
Log files
Available on request:
C:\ProgramData\Claude\Logs\cowork-service.log (22M lines showing successful VM operation)%APPDATA%\Claude\logs\main.log (MSIX virtualization check failures)%APPDATA%\Claude\logs\cowork_vm_node.log (yukonSilver unsupported + deleteVMBundle loop)
Summary
Claude Desktop on Windows fails to enable Cowork with the message "Cowork requires a newer installation — Reinstall the desktop app." The "Reinstall" button does nothing. The root cause is a broken Squirrel-to-MSIX migration path that silently leaves the MSIX package in a non-virtualized state.
Plans affected: Claude Max Plan + Codex Enterprise
OS: Windows 11 Home 10.0.26200 Build 26200
Package: Claude_1.1.9134.0_x64__pzs8sxrjxfjjc (SignatureKind: Developer)
Root Cause (fully diagnosed with log evidence)
The app checks for MSIX filesystem virtualization at:
When this path doesn't exist, the app logs:
The
yukonSilverfeature is markedstatus=unsupported, which triggers TWO destructive behaviors:cleanupVMBundleIfUnsupportedThe irony: Cowork VM works perfectly
The service log proves the VM runs fine on this machine:
[HCS] HcsCreateComputeSystem returned: hr=0x0(VM created successfully)[VM] VM started successfully[RPC] sdk-daemon is ready[RPC] API reachability: REACHABLEThe VM ran, processes completed, API was reachable — then on restart, the app checked the MSIX path, found it missing, declared Cowork unsupported, and deleted reinstall files.
Self-destructive deletion loop
The app repeatedly deletes VM bundle reinstall files every time it starts:
Environment
LocalCache\Roamingdirectory exists but has noClaudesubfolderWhat needs to be fixed
Impact
Real monetary loss across Claude Max Plan and Codex Enterprise. Hours of productive time lost diagnosing what turned out to be a missing directory in a broken migration path. 8 daily scheduled tasks for a consulting business were disrupted.
Log files
Available on request:
C:\ProgramData\Claude\Logs\cowork-service.log(22M lines showing successful VM operation)%APPDATA%\Claude\logs\main.log(MSIX virtualization check failures)%APPDATA%\Claude\logs\cowork_vm_node.log(yukonSilver unsupported + deleteVMBundle loop)