dev/vmmon error prevents startup after Catalina and 11.5 updates

[SCArtboy]

Got a new Mac with Catalina and transferred over everything from the old HighSierra (running Fusion 11.1.z), with a Win10 vm which had been running fine. Updated to Fusion 11.5 and now I get a sequence of three errors when attempting to resume the VM (attachments).

1. Could not open /dev/vmmon   (module not loaded)

2. Failed to initialize monitor device

3. Transport (VMDB) error -14: Pipe connection has been broken

Tried to re-import the VM but it's grayed out/not selectable. Tried uninstalling Fusion and then reinstalling. Still no joy.

Little help?

[Alex_Romeo]

Hi,

You can try the procedure proposed in this post:

New to VMWare on Mac. 'Could not open /dev/vmmon: Broken pipe.' ... 'Please make sure that the kerne...

1. Shut down the Virtual Machine.
2. Ensure VMware Fusion is quit.
3. Click on Apple logo on the top left of the Mac screen -> System Preferences -> Security and Privacy ->General>See if you get any messages, "System Software from VMware is being blocked" if yes, please click on Allow.
4. Re-launch Fusion.
5. Restart your virtual machine.

ARomeo

[ColoradoMarmot]

If the steps above to enable the kernel extension don't work, there's a couple of other potential causes:

- Using a time machine backup is unreliable for virtual machines.  Try copying the VM over manually using an external hard drive.

- Resuming VM's across hardware rarely works.  You'll need to force-power off the VM and then boot it from scratch.  Highly recommend a backup first, or if possible, use the old machine, resume it there, shut it down, and copy across cold.  Note that snapshots taken on the old machine should be deleted as well.