[BUG] Session disk not found (sessiondata.vhdx missing) — related to #80429, but LSA permission theory ruled out

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?

Same core error as #80429 (session disk not found, sessiondata.vhdx missing),
but with some differences that may narrow down the root cause:

failed to set session disk path: session disk not found:
C:\Users\<your-username>\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\sessiondata.vhdx

Bundle folder contents (via Get-ChildItem):

• rootfs.vhdx (8GB) present
• smol-bin.vhdx present
• sessiondata.vhdx MISSING entirely
• .auto_reinstall_attempted flag file present (dated prior to issue)
• .cowork-adopted flag file present (dated same day issue appeared)

Difference from #80429: that report's readiness check got "Access Denied"
when querying LSA for SeServiceLogonRight/SeDenyServiceLogonRight on SID
S-1-5-83-0. On my machine, I could query it successfully (secedit /export
/areas USER_RIGHTS) and confirmed:

• S-1-5-83-0 HAS SeServiceLogonRight
• S-1-5-83-0 is NOT in SeDenyServiceLogonRight

So the LSA/service-logon-permission theory doesn't explain my case — this
may point to a different or additional root cause (possibly related to the
.cowork-adopted flag and per-session disk provisioning logic specifically,
rather than a VM-platform-level permission issue).

Troubleshooting already attempted (all unsuccessful):

• Confirmed app installed entirely on C: via Get-AppxPackage
• Removed stale .auto_reinstall_attempted flag file, relaunched — no change
• Full computer restart — no change
• Help > Troubleshooting > Clear cache and restart — [fill in result if tried]

What Should Happen?

Cowork/sandboxed sessions should start normally without a session disk error.

Error Messages/Logs

failed to set session disk path: session disk not found: C:\Users\<username>\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\sessiondata.vhdx
Restarting Claude or your computer sometimes resolves this. If it persists, you can reinstall the workspace or share your debug logs to help us improve.

Steps to Reproduce

Open a Cowork chat (or any sandboxed session)

Claude-logs-2026-08-01T21-40-49-983Z.zip

in the Windows desktop app.

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.220 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Tried reinstalling and everything and checked all possible duplicates of errors