[BUG] Missing HCS services: vfpext — confirmed missing even in official Windows 11 ISO (install.esd), after DISM repair and full Hyper-V reinstall
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?
aClaude Desktop's Cowork tab shows "Missing HCS services: vfpext" and remains permanently disabled, even after an exhaustive investigation confirming the underlying driver is genuinely absent from every possible source, including a fresh official Windows 11 ISO.
What Should Happen?
aCowork should either successfully enable (if the detection is a false positive, as suggested in issue #80122), or Anthropic should provide a clear remediation path for this specific Windows configuration where vfpext.sys is missing even from the official Windows 11 install media.
Error Messages/Logs
Steps to Reproduce
a1. Open Claude Desktop on Windows 11 Pro
- Click on the Cowork tab
- 3. Tooltip shows "Missing HCS services: vfpext"
- 4. Cowork tab is disabled and cannot be used
Environment checks performed:
- Get-Service vmcompute, hns -> both Running
- - Test-Path C:\Windows\System32\drivers\vfpext.sys -> False
Remediation attempts (all failed to produce vfpext.sys):
- DISM repair:
- DISM /Online /Cleanup-Image /RestoreHealth
- Completed 100% successfully. vfpext.sys still absent afterward.
- SFC scan:
- sfc /scannow
- Result: "Windows Resource Protection did not find any integrity violations." File still missing.
- Full Hyper-V feature removal + reinstall (two reboots):
- Disabled Hyper-V via "Turn Windows features on or off", rebooted, re-enabled, rebooted again. vfpext.sys still absent.
- Extracted directly from official Windows 11 installation media:
- Downloaded the Windows 11 ISO via the official Microsoft Media Creation Tool, mounted it, then mounted the install image directly:
- Dism /Mount-Image /ImageFile:E:\sources\install.esd /Index:6 /MountDir:C:\WimMount /ReadOnly
- Mount succeeded 100%. Checked:
- Test-Path C:\WimMount\Windows\System32\drivers\vfpext.sys
- Result: False
This last result is the most significant finding: the driver is not present even inside a clean, official Windows 11 install image straight from Microsoft's servers. This suggests either the driver isn't shipped for this Windows edition/build/language combination, or Cowork's detection logic is checking for the wrong condition entirely (e.g. checking for a Running service rather than a properly registered on-demand driver, as suggested in #80122).
Related/duplicate issues: #74649, #77277, #78858, #78866, #80584, #81396, #80122
Claude Model
None
Is this a regression?
Yes, this worked in a previous version
Last Working Version
_No response_
Claude Code Version
N/A - Claude Desktop (Cowork), not CLI
Platform
Anthropic API
Operating System
Windows
Terminal/Shell
Windows Terminal
Additional Information
_No response_
3 Comments
Update: Resolved on my end. The root cause and fix were posted by @owenaslin in #80122 — vfpext.sys ships with the Containers optional feature, not with Hyper-V, which is why enabling/reinstalling Hyper-V (as I did above) never brought it back.
Fix that worked for me:
Reboot, then Help → Troubleshoot → Clear Cache & Restart in Claude Desktop (the feature-check result appears to be cached, so it kept reporting the stale error until I cleared it).
Cowork is now enabled and working. Thanks @owenaslin for tracking this down — this should probably be consolidated with #80122 as the canonical fix thread.
Closing since this is resolved for me, but flagging for Anthropic's visibility before I do:
The underlying issue is a genuine product gap, not user error: Cowork's feature-detection docs/UI never mention that the Containers optional feature (not Hyper-V) is what provides vfpext.sys. Multiple users across #74649, #77277, #78858, #78866, #80584, #81396, #80122, and this issue burned significant time reinstalling/repairing Hyper-V — which was never going to fix it — because nothing in the error message or troubleshooting docs points at Containers.
Two concrete asks for a real fix:
Leaving this closed as resolved on my end, with #80122 as the reference thread with the actual root cause and fix.
This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.