VMware cause Hypervisor error 0x20001

Question

Hi everyone,

On May 27th, 2026, I updated my Windows 11 installation with update KB508973, and after the update I was no longer able to use any of my virtual machines in VMware Workstation.

Whenever I try to start a virtual machine, Windows freezes for a few seconds, then the screen goes black and eventually shows the error:

HYPERVISOR_ERROR (0x20001)

I attempted to uninstall the update, but Windows did not allow me to remove it. A few days later, I decided to reset Windows completely (removing everything). Right after the reset, I installed VMware again and tried to open a VM, but the exact same issue still occurs.

What I have already checked:

Verified in BIOS that hardware virtualization is enabled.

Ensured the following Windows features are unchecked under Turn Windows features on or off:

Hyper‑V

  Virtual Machine Platform
  
     Windows Hypervisor Platform
     
        Windows Sandbox
        

Despite all of this, VMware still triggers the same Hypervisor error and freezes the system.

Is there anything else I should check, or is this update known to cause conflicts with VMware’s virtualization drivers?

Thanks in advance for any help.

Answer 1

Hello Aarón García,

Welcome to Microsoft Q&A forum.

Based on your description, the real cause of this might come from the fact that the hypervisor on newer build can still run even if Hyper-V is unchecked. In this case, please try to follow these steps.

• Type "Command Prompt" in the search bar and select "Run as administrator"
• Type bcdedit /set hypervisorlaunchtype off and press Enter.
• Type "Windows Security" in the search bar and press Enter.
• Go to Device Security > Core Isolation.
• Turn off "Memory Integrity".
• Type "Group policy" in the search bar and press Enter.
• Go to Computer Configuration > Administrative Templates > System > Device Guard
• Set Turn On Virtualization Based Security to Disabled
• Restart your computer.

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Answer 2

The HYPERVISOR_ERROR bug check 0x00020001 indicates that the Windows hypervisor has encountered a fatal error. The context shows this stop code is specifically tied to hypervisor failures and, in some cases, to interactions with virtualization features and hardware/BIOS configuration.

From the available information:

• Bug check 0x20001 (HYPERVISOR_ERROR) is raised when the hypervisor encounters a fatal condition.
• Similar issues are documented on older Windows Server/Hyper‑V stacks where specific CPU features or virtualization interactions caused hypervisor crashes (for example, VMCS caching on certain Intel CPUs, or XRSTOR handling with Linux guests). These are low‑level hypervisor faults, not simple application errors.
• A BIOS/firmware or hardware‑virtualization configuration problem can prevent the hypervisor from loading or functioning correctly, and in some cases requires a BIOS update or configuration change.

Given what has already been tried (disabling Hyper‑V related Windows features, full reset, reinstalling VMware) and the fact that the stop code is a hypervisor‑level failure, the next checks are:

1. Verify and, if necessary, update system BIOS/UEFI firmware to the latest version from the OEM, as outdated firmware and incorrect reporting of virtualization capabilities can cause hypervisor failures.
2. Re‑check BIOS/UEFI virtualization‑related options (VT‑x/AMD‑V, IOMMU/VT‑d, any “Secure Mode Extensions” or similar) and ensure they are configured according to the OEM guidance for running third‑party hypervisors.
3. If the issue persists, collect a memory dump and analyze it with the !analyze debugger extension as described for bug check 0x20001 to identify the exact failing hypervisor component or instruction path.

If the hypervisor continues to crash with 0x20001 even after a clean reset and BIOS verification/update, this indicates a low‑level incompatibility or defect that requires further investigation with a kernel debugger and likely engagement with Microsoft or the OEM, as it is not a VMware‑only configuration issue.

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References:

• Bug Check 0x20001: HYPERVISOR_ERROR
• "0x20001" Stop error when you start a Linux VM in Windows Server 2008 R2 SP1
• "STOP: 0x0000001a" error message on a computer that has an Intel Westmere processor together with the Hyper-V role installed on Windows Server 2008 or on Windows Server 2008 R2
• A BIOS update may be required for some computers to install the Hyper-V Role and/or start Hyper-V virtual machines