Full file backups attempt to create snapshot even if disabled

Hello all.

I am seeing the following error message in my logs:

backupcom->AddToSnapshotSet(&(Server->ConvertToWchar(selected_vols[i])[0]), GUID_NULL, &additional_refs[i].volid) failed. VSS error code VSS_E_VOLUME_NOT_SUPPORTED
Creating snapshot of “E” failed.

This is for a USB thumb drive that I usually keep connected to the client (FWIW, I supply /optional in the configuration, accordingly).

My server has a general configuration to create both image and file backups only for drive C: on most of my machines. For this particular client, I have overridden the configuration to backup drives E: F: and G: as well (all USB thumbs with /optional). All three drives are reporting similar errors.

On a different client, I have thumb drives as E: and F: with a similar configuration. Likewise, both drives on that client try to create snapshots and fail.

Both clients have “Volumes to snapshot in groups during file backups = C”. Same for image backups (which aren’t even attempted for E: F: or G:, despite having “Volumes to backup = ALL” overriding my general configuration of “Volumes to backup = ALL_NONUSB”, but that would seem to be a separate issue).

I have tried setting “Default directories to backup = …E:\…” as well as “Default directories to backup = …E:\|E/optional…” and both fail.

These thumb drives must be FAT32. NTFS is not an option.

This isn’t a showstopper bug for me, but I would very much like to back up my thumb drives.

Could some kind user please try to reproduce this so that I know that it isn’t just me that is affected by this?