VMware Workstation 15.5 unrecoverable error (vcpu-0) Exception 0xc0000005 (access violation)

[jsalton1]

Hi,

I get this error on all my VMs after having installed Workstation on a new Windows 11 machine. This includes new VMs created on the Win 11 host. I tried reducing the number of CPUs/cores to 1/1 but the performance is terrible and unuseable.

Does anyone have a proper fix where I can get the performance back and allocate more than one core to a VM please?

Thanks,

[wila]

Hi,

Check the vmware log file and search for a line that has "monitor mode" in it.

There's either:

monitor mode ULM

or

monitor mode CPL0

If your log file has the line:

monitor mode ULM

then that means that you are running in User Level Mode and thus Workstation cannot use VMware's hypervisor, but instead it has to go through the Hypervisor API that Microsoft provides.

Only when Monitor mode returns CPL0 it is running in ring 0, a.k.a. no hypervisor.

Monitor mode CPL0 (Current Privilege Level 0) is required for VMware Workstation to be able to use their own hypervisor.

See also:

https://communities.vmware.com/t5/VMware-Workstation-Pro/MikroTik-RouterOS-boot-speed-is-drastically...

In order to turn off ULM/Hyper-V mode, run the following command at the host in windows command-line with Administrator privileges:

bcdedit /set hypervisorlaunchtype off

Reboot the system to activate your changes.

If you want to go back to Hyper-V mode again, then you can enable it like this:

bcdedit /set hypervisorlaunchtype auto

See also:

• Workstation 16 Pro Error "Virtualized Intel VT-x/EPT is not supported on this platform
• https://kb.vmware.com/s/article/2146361

Note that you also might have to disable Memory Integrity.

Windows Security -> Device Security -> Core Isolation details

Don't forget to reboot the host after making any of these changes.

Best of luck,

--
Wil