Today while creating new VMs from a template I got the error “the server fault invalidargument had no message” when editing the VM settings, the settings were modified successfully but the error was present whether a change had been made or not to the settings of the VM.
A quick search of the web suggested removing said VM from the inventory and re-adding from the datastore, for many this fixed the issue but not for me.
Another suggested removing and reading the Host from the cluster which I did and still no joy. Finding little else to go on I elected to simply restart the host the VM/template was originally on.
Lo and behold this fixed the issue!