[BUG] Missing HCS services: vfpext — corrupt component manifest (CSI) blocks driver deployment, manual load fails with ERROR 193

[PanzerIhnen]

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

Note: this is a Claude Desktop / Cowork bug, not the Claude Code CLI.

Cowork shows "Missing HCS services: vfpext" and the tab remains disabled.

Diagnosis performed:

• vmcompute and hns services: Running (Get-Service)
• vfpext: not installed as a service (sc.exe query vfpext -> error 1060)
• C:\Windows\System32\drivers\vfpext.sys: does not exist (Test-Path -> False)
• Full Hyper-V feature disable/enable cycle: does not restore the driver
• DISM /RestoreHealth + sfc /scannow: completed without fixing the issue

Root cause found in CBS.log:
CSI Scavenge: Skipping content retention check due to missing component
manifest: amd64_microsoft-windows-hyper-v-vfpext_31bf3856ad364e35_10.0.26100.8521_none_9c6e9b959bce5329

The manifest file for this component IS physically present under
WinSxS\Manifests, but CSI treats it as missing/unreadable, which
prevents the servicing transaction from ever completing and copying
vfpext.sys into System32\drivers. WinSxS also contains several stale
InFlight transactions for this same component (versions 7309, 7920,
8115, 8457, 7705), suggesting a Windows Update that never completed
cleanly for this driver.

Manual workaround attempted (unsuccessful):

1. Copied vfpext.sys from WinSxS (version 10.0.26100.8875) to
   System32\drivers manually
2. Registered it as a kernel driver service:
   sc.exe create vfpext type= kernel start= demand binPath= C:\Windows\System32\drivers\vfpext.sys
3. sc.exe start vfpext -> fails with ERROR 193 (ERROR_BAD_EXE_FORMAT)

This suggests vfpext is an NDIS filter driver that cannot be started
via a plain sc start — it likely requires proper NDIS binding via its
.inf (wnetvsc_vfpp.inf, also present in WinSxS) processed through the
normal feature installer, which is blocked by the corrupt manifest
described above.

What Should Happen?

Either the Hyper-V feature installer successfully repairs/redeploys
the vfpext component despite the CSI manifest issue, or Cowork's
troubleshooting docs cover this specific failure mode (corrupt CSI
manifest + NDIS filter driver that can't be manually registered), so
Cowork can start normally.

Error Messages/Logs

sc.exe query vfpext:
[SC] EnumQueryServicesStatus:OpenService ERROR 1060: 
El servicio especificado no existe como servicio instalado.

CBS.log:
CSI Scavenge: Skipping content retention check due to missing component 
manifest: amd64_microsoft-windows-hyper-v-vfpext_31bf3856ad364e35_10.0.26100.8521_none_9c6e9b959bce5329

sc.exe start vfpext (after manual registration):
[SC] StartService con error 193.

Steps to Reproduce

1. Open Claude Desktop on Windows 11 Pro (build 10.0.26100)
2. Click the Cowork tab
3. Observe "Missing HCS services: vfpext" and the tab stays disabled

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

No response

Claude Code Version

Claude 1.24012.9 (03c61d) 2026-07-24T04:59:17.000Z

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

N/A — this is Claude Desktop (the consumer app), not the Claude Code CLI.
N/A — consumer Claude Desktop app (Pro/Max/Team plan), not using the API directly.
N/A — bug occurs in the Claude Desktop GUI (Cowork tab), not in a terminal.
PowerShell was used only for diagnostics, shown in the Error message/logs section.

[PanzerIhnen]

Resolved after several additional reboots today — likely a pending
Windows Update finally completed and repaired the corrupt vfpext
manifest. Leaving the diagnostic details above in case they help
anyone with the same symptom.

[sauroweb]

Environment: Windows, Cowork blocked with "Missing HCS service: vfpext"

Confirming the same deployment gap pattern reported here.

sc.exe query vfpext → error 1060 (service does not exist)
Test-Path C:\Windows\System32\drivers\vfpext.sys → False (driver file missing from the active location)
Get-ChildItem -Recurse -Filter vfpext.sys on WinSxS shows the file is present in the component store, across 3 builds:
10.0.26100.8521 — 2026-06-10
10.0.26100.8875 — 2026-07-15
10.0.26100.8972 — 2026-08-12 (latest)

So the package is staged in WinSxS but never gets deployed to System32\drivers, which points to a CSI manifest issue rather than a missing component.

Already tried, no effect:

DISM /Online /Cleanup-Image /RestoreHealth + reboot
sfc /scannow + reboot
Clearing Claude's cache (Help → Troubleshoot) — ruled out as a Cowork-side false positive

Happy to run any additional diagnostic commands if useful.