Error Message

V-79-57344-38374 - A quiesced snapshot could not be created for the virtual machine (DC)ha-datacenter(DC)\vm\VA-THIN2019-67. Alternatively, a crash-consistent snapshot was created. It is recommended to have a quiesced snapshot of a VM to ensure data consistency of the file system and all VSS-supported applications.
 

The backup jobs running on Backup Exec server installed on Windows Server 2019, 2016 & 2012 R2 operating system may take a lot of time and complete with exception for all the Windows 2019 VM (build 17758). This behavior was not seen on Vsphere 6.5.

Quiescing fails while backup of virtual machine that are created with EFI boot partition, which is default for vSphere 6.7. Windows 2019 virtual machines created with MBR boot partition do not display any quiescing error during backup. The backup Job of VMs on vSphere 6.5 having EFI boot partition (default on vSphere 6.5 is BIOS) works fine. The Issue is only with VMs created on vSphere 6.7 with default boot partition as EFI.
 

This issue is resolved in Windows Server version 1809 and all versions of Windows Server 2019 OS Build 17763.1012. For more information, see January 23, 2020—KB4534321 (OS Build 17763.1012).
VMware Reference article