I cannot use Calude CoWork...

Question

I cannot use Calude CoWork...

Luca Le Helley 0

Missing vfpext.sys driver — Hyper-V Host Compute Service incomplete

System

Device: GEEKOM A5 Pro mini PC (AMD Ryzen)

OS: Windows 11, Version 25H2, Build 26200.8457

Fully patched as of 7/12/2026 (KB5094126, KB5094135, KB5087051 all installed)

Problem

Hyper-V's Host Compute Service stack is incomplete. Specifically, the vfpext driver (VFP switch extension, part of the Hyper-V extensible switch) is missing from the live system, even though it should be installed as part of the Hyper-V feature set.

Symptom

C:\Windows\System32\drivers\vfpext.sys does not exist on disk (Test-Path returns False).

Get-Service vfpext returns "Cannot find any service with service name 'vfpext'."

HNS and vmcompute services ARE present and running normally:

Status   Name               DisplayName
------   ----               -----------
Running  HNS                Host Network Service
Running  vmcompute          Hyper-V Host Compute Service

This is blocking a third-party application (Claude Desktop's "Cowork" feature) that requires the full HCS stack, but the root issue is clearly Windows-side, not app-side.

What's been confirmed working

Virtualization enabled in BIOS/UEFI (SVM Mode)

systeminfo confirms a hypervisor is detected

Hyper-V, Virtual Machine Platform, and Containers optional features are all enabled:

Get-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All   → Enabled
Get-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform  → Enabled

sfc /scannow — no integrity violations found

The vfpext driver payload IS present in the component store:

Get-ChildItem -Path "C:\Windows\WinSxS" -Recurse -Filter "vfpext.sys"

returns valid entries, including one dated 7/11/2026 (post-repair-attempt), e.g.:

C:\Windows\WinSxS\amd64_microsoft-windows-hyper-v-vfpext_31bf3856ad364e35_10.0.26100.8457_none_9c7be3af9bc41d03\vfpext.sys

So the file exists in the servicing store but is not being deployed to System32\drivers.

Steps already attempted (all unsuccessful)

DISM /Online /Cleanup-Image /RestoreHealth (Windows Update source) — completed successfully, no effect on vfpext

sfc /scannow — completed, no integrity violations

Full disable/re-enable cycle of the Hyper-V feature — no effect

Manual attempt to install the WinSxS package directly via dism /add-package — rejected (error 87, "no packages found that require processing")

Checked Hyper-V Virtual Switch Manager → Default Switch → Extensions: only "Microsoft Windows Filtering Platform" and "Microsoft NDIS Capture" are listed; the VFP switch extension does not appear at all

Full in-place repair install via mounted Windows 11 25H2 ISO (setup.exe, "Keep personal files and apps") — completed successfully, all files/apps preserved, but vfpext is still missing afterward

Question for support

Given that a full in-place repair install did not restore this driver, what is required to get the vfpext component properly registered and deployed on this system? Is there a known issue with this component on Build 26200.8457, or a deeper CBS/servicing-level cause that requires escalated diagnostics?

Attached/available if requested

CBS.log (C:\Windows\Logs\CBS\CBS.log)

DISM.log (C:\Windows\Logs\DISM\dism.log)

Missing vfpext.sys driver — Hyper-V Host Compute Service incomplete

System

Device: GEEKOM A5 Pro mini PC (AMD Ryzen)

  OS: Windows 11, Version 25H2, Build 26200.8457
  
     Fully patched as of 7/12/2026 (KB5094126, KB5094135, KB5087051 all installed)
     
     ## Problem

     Hyper-V's Host Compute Service stack is incomplete. Specifically, the **vfpext** driver (VFP switch extension, part of the Hyper-V extensible switch) is missing from the live system, even though it should be installed as part of the Hyper-V feature set.
     
     ## Symptom

     `C:\Windows\System32\drivers\vfpext.sys` does not exist on disk (`Test-Path` returns `False`).
     
     `Get-Service vfpext` returns "Cannot find any service with service name 'vfpext'."
     
     HNS and vmcompute services ARE present and running normally:
     
     ```powershell
     Status   Name               DisplayName

Running HNS Host Network Service Running vmcompute Hyper-V Host Compute Service ```

     This is blocking a third-party application (Claude Desktop's "Cowork" feature) that requires the full HCS stack, but the root issue is clearly Windows-side, not app-side.
     
     ## What's been confirmed working

        Virtualization enabled in BIOS/UEFI (SVM Mode)
        
           `systeminfo` confirms a hypervisor is detected
           
              Hyper-V, Virtual Machine Platform, and Containers optional features are all enabled:
              
              ```powershell
              Get-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All   → Enabled

Get-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform → Enabled ```

                 `sfc /scannow` — no integrity violations found
                 
                    The vfpext driver payload IS present in the component store:
                    
                    ```powershell
                    Get-ChildItem -Path "C:\Windows\WinSxS" -Recurse -Filter "vfpext.sys"
                    ```
                    
                    returns valid entries, including one dated 7/11/2026 (post-repair-attempt), e.g.:
                    
                    ```yaml
                    C:\Windows\WinSxS\amd64_microsoft-windows-hyper-v-vfpext_31bf3856ad364e35_10.0.26100.8457_none_9c7be3af9bc41d03\vfpext.sys
                    ```
                    
                    So the file exists in the servicing store but is not being deployed to `System32\drivers`.
                    
                    ## Steps already attempted (all unsuccessful)

                       `DISM /Online /Cleanup-Image /RestoreHealth` (Windows Update source) — completed successfully, no effect on vfpext
                       
                          `sfc /scannow` — completed, no integrity violations
                          
                             Full disable/re-enable cycle of the Hyper-V feature — no effect
                             
                                Manual attempt to install the WinSxS package directly via `dism /add-package` — rejected (error 87, "no packages found that require processing")
                                
                                   Checked Hyper-V Virtual Switch Manager → Default Switch → Extensions: only "Microsoft Windows Filtering Platform" and "Microsoft NDIS Capture" are listed; the VFP switch extension does not appear at all
                                   
                                      **Full in-place repair install** via mounted Windows 11 25H2 ISO (`setup.exe`, "Keep personal files and apps") — completed successfully, all files/apps preserved, but vfpext is still missing afterward
                                      
                                      ## Question for support

                                      Given that a full in-place repair install did not restore this driver, what is required to get the vfpext component properly registered and deployed on this system? Is there a known issue with this component on Build 26200.8457, or a deeper CBS/servicing-level cause that requires escalated diagnostics?
                                      
                                      ## Attached/available if requested

                                         CBS.log (`C:\Windows\Logs\CBS\CBS.log`)
                                         
                                            DISM.log (`C:\Windows\Logs\DISM\dism.log`)

AE 0 Reputation points

2026-07-17T16:52:50.1466667+00:00
Hi,

I had a similar problem and tried re-installing claude desktop multiple times, however, couldn't get co-work to work.
I asked Claude to help me and was able to fix, the summary of what we did is below. The most strange part is that Virtualization was enabled, so, I simply disabled / enabled that, re-started and it worked.

Here's the full troubleshooting path we worked through to get Cowork running on your Lenovo T490S (Windows 10 Pro):

Confirmed subscription eligibility — Claude Pro covers Cowork access, so that wasn't the issue.

Checked BIOS virtualization — Went into BIOS (Enter, then F1 on boot) → Security → Virtualization, and confirmed Intel Virtualization Technology was enabled. Toggled it off and back on, then restarted twice as an extra reset.

Verified Hyper-V hardware requirements — Ran systeminfo in PowerShell and confirmed all four Hyper-V requirements passed (VM Monitor Mode Extensions, Virtualization Enabled In Firmware, Second Level Address Translation, Data Execution Prevention) — all showing Yes.

Found the actual blocker — Ran Get-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform in a properly elevated PowerShell window (the first attempt failed because the window wasn't truly running as admin, even though it looked like it). This revealed the real issue: Virtual Machine Platform was disabled in Windows.

Fixed it — Ran Enable-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform -All, then restarted the laptop for the change to take effect.

Result — Opened Claude Desktop after the restart, and Cowork appeared and is now working.

The root cause: Windows' Virtual Machine Platform feature — which Cowork needs to run its isolated task environment — was simply switched off at the OS level, separate from BIOS settings, admin rights, or hardware capability, all of which were fine the whole time.

3 answers

Your answer

AE 0 Reputation points

2026-07-17T16:52:50.1466667+00:00

Hi,

I had a similar problem and tried re-installing claude desktop multiple times, however, couldn't get co-work to work.
I asked Claude to help me and was able to fix, the summary of what we did is below. The most strange part is that Virtualization was enabled, so, I simply disabled / enabled that, re-started and it worked.

Here's the full troubleshooting path we worked through to get Cowork running on your Lenovo T490S (Windows 10 Pro):

Confirmed subscription eligibility — Claude Pro covers Cowork access, so that wasn't the issue.

Checked BIOS virtualization — Went into BIOS (Enter, then F1 on boot) → Security → Virtualization, and confirmed Intel Virtualization Technology was enabled. Toggled it off and back on, then restarted twice as an extra reset.

Verified Hyper-V hardware requirements — Ran systeminfo in PowerShell and confirmed all four Hyper-V requirements passed (VM Monitor Mode Extensions, Virtualization Enabled In Firmware, Second Level Address Translation, Data Execution Prevention) — all showing Yes.

Found the actual blocker — Ran Get-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform in a properly elevated PowerShell window (the first attempt failed because the window wasn't truly running as admin, even though it looked like it). This revealed the real issue: Virtual Machine Platform was disabled in Windows.

Fixed it — Ran Enable-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform -All, then restarted the laptop for the change to take effect.

Result — Opened Claude Desktop after the restart, and Cowork appeared and is now working.

The root cause: Windows' Virtual Machine Platform feature — which Cowork needs to run its isolated task environment — was simply switched off at the OS level, separate from BIOS settings, admin rights, or hardware capability, all of which were fine the whole time.

Answer 1

To the OP, I had this exact same problem and applied almost all of the same fixes you tried. As I was checking things, from PowerShell I ran "Get-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform" and noted that the status was "disabled". I then ran "Enable-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform -All" and it did not require a reboot. I then checked "Get-Service vfpext" and didn't get an error message this time (!!!). It was installed and status was Stopped.

Then all I had to do was close Claude (ensuring to end task from Task Manager). When I opened Claude, again, boom, the Cowork option was in the chat!

Would love to hear if that helps you.

Answer 2

Aaryaman 0

Enable-WindowsOptionalFeature -Online -FeatureName VirtualMachinePlatform -All -NoRestart run the above command in elevated powershell

0 comments

Answer 3

Hello Luca,

Thank you for providing such a comprehensive description of your troubleshooting. Based on the information you’ve shared, I could not find any Microsoft documentation indicating that vfpext.sys is expected to be installed as a standalone service or always present under C:\Windows\System32\drivers on Windows 11 25H2. Likewise, there are currently no published known issues for Build 26200.8457 indicating that the absence of vfpext.sys represents a servicing or CBS regression.

6e28d74f0f1edc92a04a821de7ace2cad49b0357.pdf

Since DISM /RestoreHealth, SFC, disabling and re-enabling Hyper-V, and even an in-place repair installation all completed successfully without restoring the file, this suggests the Windows component store is healthy and that the component is either no longer deployed in the manner expected by the application or is loaded only when required by specific Hyper-V networking scenarios, rather than indicating corruption.

6e28d74f0f1edc92a04a821de7ace2cad49b0357.pdf

To determine whether this is a Windows issue or an application compatibility issue, could you confirm whether another Windows 11 25H2 system with the same Hyper-V features enabled exposes vfpext.sys under C:\Windows\System32\drivers and whether the Claude Desktop “CoWork” feature officially documents vfpext.sys as a prerequisite? If the application is relying on the presence of a specific driver that is no longer deployed in recent Windows builds, this would be an application compatibility issue rather than a Windows servicing failure.

If you can also provide the output of Get-WindowsCapability -Online, Get-NetAdapterBinding, and the relevant CBS.log entries related to Hyper-V component installation, we can further determine whether any Hyper-V networking component failed to install or whether the current behavior is by design.