Registering a VM created by a slightly newer version of ESXi

Related to the previous post, I’ve downgraded one of my ESXi hosts to ESXi 7U1c in a fit of frustration and sleep deprivation.

Now comes the headache of re-configuring this host, along with registering VMs that were created by a newer version of ESXi 7. Specifically, 7U2.

Et eu, VMs?

Now I didn’t really use any special 7U2-specific configuration for my VMs, so let’s go ahead and cheat our way into mutating their VMX configs so we can register them.

1. Remove invalid VM from inventory
2. Enable SSH on ESXi Host
   Lots of guides online for this already – use your favourite method, via vCenter, via ESXi web UI, via DCUI, etc.
3. Open a vi session to your VM config file
   Assuming you’ve got your VMs tucked away in some datastore located in /vmfs/volumes, go ahead and do a vi /vmfs/volumes/<DATASTORE_NAME>/<VM_NAME>/<VM_NAME>.vmx
4. Edit the virtualHW.version
   In my particular case, I dropped it from 19 to 18.
   List of virtualHW versions: https://kb.vmware.com/s/article/1003746
5. Register VM