I have just updated to 8.1.2 and have tested running backups on Windows server 2019.
Agent based backup worked fine but when I run a VM backup it failed.
Netbackup report: an error occurred while quiescing the virtual machine.
If I look in eventviewer on the server, there is VSS errors:
An expected hidden volume arrival did not complete because this LUN was not detected.
There is no problem running a snapshot from vcenter.
It is incredible that Netbackup does not support Windows server 2019 yet.
First preview release was march 2018, a year ago. And GA released in october 2018.
When will Windows server 2019 be supported in NetBackup?
NBU 8.1.2 on Windows 2012
Vcenter 6.7 U1
Supported guest operating systems for VMware
NetBackup for VMware supports backup and recovery of the entire virtual machine
for all guest operating systems that are supported by VMware. To determine VMware
support for a particular operating system, consult the VMware Compatibility Guide.
So, what you are experiencing is NOT a support issue.
Have you tried to do a snapshot from vcenter with quiescing option selected?
The default is without quiescing.