During a rebuild of a Dell EMC Avamar backup solution, we ran into an issue where VMware was logging, “An error occurred while quiescing the virtual machine. See the virtual machine’s event log for details.” for a few virtual machine backups. While testing, we noticed that it was not occurring on all backups.
On a functional backup with no errors, a machine had a service called VMware Snapshot Provider and this service was set to manual. On the machine I was troubleshooting, this service didn’t even show up in the list. I opted to uninstall tools, restart the server, and then reinstall VMware tools. Upon inspection of the services listing this time, the service was present and set to manual. I tested a backup and there were no failures and the machine backed up fine.
I tested another virtual machine that I knew previously worked and this time I went to services and set the VMware Snapshot Provider service to disabled and initiated a backup on the Avamar UI (AUI). As expected, VMware logged an event as noted above.
In conclusion, if you notice this error occurring, regardless if there were no errors previously, check for this service. The service can be reinstalled by invoking the VMware Tools installer again and changing the installed features. If all else fails, just remove, reboot, and re-install.