Depending on what other backup, build, or restoration solutions you have in place you may see a “virtual disk is not a multiple of…” error when backing up with Veeam.
The error sounds quite ominous like a major disk issue on the host. The good news is it ends up it is a quick fix on the VM using the GUI interface.
Open up the VM settings and resize the virtual drive from the weird size such as 79.435346435 GB to 80GB and the same for the secondary or other disks for example 250.45346324GB to 251GB. Then access the VM and expanded the drives via the OS.
If it is already a “normal” drive size try going up another drive size for example 80GB to 81GB and expand the drive in the OS.
Then test the backup job.
Credit: Veeam KB article https://www.veeam.com/kb1848