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Cannot start GNS3 VM in VMware Workstation 15.5.5 build-16285975

Hi all, I have just update to VMware Workstation 15.5.5 build-16285975 and Windows 10 20H1.

Then I cannot start GNS3 VM.

I got error:

VMware Workstation does not support nested virtualization on this host.

Module 'MonitorMode' power on failed.

Failed to start the virtual machine.

Please how I can fix it.

Thank you.

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Hi Reyes858,

I upgraded WSL 1 to WSL 2 to use both Hyper-V and VMware.

Then I disabled Hyper-V, WSL feature.

I uninstall VMware Workstation and reinstall.

Finally, I change the visualization parameter in BIOS but not resolve the error.

Thanks.

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Hi nguyennoi1992,

By default, the GNS3 VM is set up to support nested virtualization, and if you are seeing this error message, it is because there is something going on in your host system that is preventing nested virtualization from working.

If you go to Virtual Machine Settings > Hardware > Processors and uncheck "Virtualize Intel VT-x/EPT or AMD-V/RVI", you should be able start and use the VM. However, be advise that KVM support (nested virtualization) will be disabled, and so you will not be able to run things like Cisco VIRL images. This may not be a requirement for you, but it is for me, and so I don't really consider this a solution...

What I found to be the actual problem is that I am running a version of Windows that also supports Hyper-V, and it turns out that if Hyper-V is turned on, nested virtualization won't work in VMWare. The reason why is beyond my pay grade. But, if you don't mind turning off Hyper-V, the fix is simple and this forum post will show you how: https://communities.vmware.com/thread/634674

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