Ubuntu 20 VM won't reboot under CORE 12.0-U8.1

[danb35]

I built my parents a NAS on a MicroServer Gen8 (Xeon E3-1220L, 16 GB RAM, pair of 16 TB disks mirrored), and created a VM (1 core, 1 GB RAM, UEFI boot) for Ubuntu Server 20 to run Pi-Hole for them. It runs well--starts at boot and works just fine. Until something happens that requires I reboot the VM--what happens then is that it goes through its shutdown sequence, and then just hangs. If I go into the TrueNAS UI, I can then stop (i.e., hard "power off") the VM, start it again, and it boots and runs just fine. But the VM simply won't "reboot" without going through that dance at the TrueNAS UI. Any ideas where I should be looking to figure out why?

 

[Cellobita]

Had the exact same issue, never got it to work reliably. It may be just a coincidence, but Ubuntu 22.04 (I've upgraded both systems where I had 20.04 installed) seems less prone to this.

 

[sretalla]

Maybe try with 2 cores (or 1 core, 2 threads).

I seem to recall some strangeness around only a single core for a VM.