You may receive an error when performing any operation on a Unidesk machine, including backups or even just powering the machine on:

A general system error has occurred:vim.fault.genericvmconfigfault

If your investigation leads you to check the snapshot configuration, and the snapshots are just "broken", you might not be able to delete them or clean up.

Let's assume you have an MM where you can't delete or create snapshots. You may also have trouble powering it on, depending on just what the damage you have is.

One possibility is that you just need to destroy any and all snapshots on the MM. This will have the effect of rolling the User Layer back to the oldest snapshot, which might be a while ago depending on when everything went bad. Check the timestamps on the base disks to see just how far back you're going, so you can at least tell the customer. It's likely to be the date of the last successful Unidesk Backup as well.

So, to destroy any and all snapshots on an MM, shut the VM down. Then Edit Settings. Look at the last two disks, the User Layer disks, and if they're anything other than the base disk (if they're the -0000x.vmdk files), remove them. Then add back just the base disks. Make sure you keep them in the right order: V1 first and V0 second.

Then Browse Datastore on the CP and Layers tier. Drill down to the User Layer folder and delete any -00000X.vmdk files.

Then Browse Datastore on the Boot Images tier, drill down to the VM folder, and delete the .VMSD and .VMSN files.

You should now be able to manually create and delete a snapshot, so do that. Then power the machine on.