It turned out that a bunch of the VMs we were vMotioning from the old environment had the cpuid.corePerSocket advanced setting set in the .vmx file, and this can cause ESXi 6.5 to enter a state of panic, and in our case it certainly did.
Upgrading the hosts to 6.5a, like the knowledgebase article states, alleviated the issue and we did not experience PSOD’s again while migrating the 100+ VMs from the old environment to the new one.
Just a quick post about something I experienced at a client, with ESXi 6.0 hosts, today:
If you have trouble performing VMware snapshots, and see a msg.snapshot.error-QUIESCINGERROR error, check the host time settings and NTP.
In this case, snapshots of VMs located on other hosts in the cluster were fine, but once a VM was moved to the new host, snapshot operations failed after an hour or so.
It turns out a new host in the cluster was not properly set up to use NTP, and time drift between the host and the vCenter caused the snapshot failures. Correcting the time on the host and configuring NTP resolved the issue.
Always remember: If the problem isn’t DNS, it almost certainly is NTP.