Windows server file backup failed

Windows client file backup failed.
I try to backup only one folder.
First i create shadowdisk and backup folder from it.
There are log:

Errors 26.04.21 19:15 backupcom->AddToSnapshotSet(&(Server->ConvertToWchar(selected_vols[i])[0]), GUID_NULL, &additional_refs[i].volid) failed. VSS error code VSS_E_VOLUME_NOT_SUPPORTED
Errors 26.04.21 19:15 Creating snapshot of “databases” failed.
Errors 26.04.21 19:34 Referencing snapshot on “mail-01” for path “databases” failed: FAILED
Errors 26.04.21 19:34 Client mail-01 went offline.
Errors 26.04.21 19:37 Backup failed

In other client i did not make shadowdisk, and try to backup one folder, but there are errors:

Errors 22.04.21 12:22 Removing snapshot on “net-dc3” for path “.symlink_{0F94B1CE-FB61-4610-9561-8663BF449492}-{6CCD2376-C654-497E-8CB3-D74E99B2E656}” failed: FAILED
Errors 22.04.21 12:22 Client net-dc3 went offline.
Errors 22.04.21 12:22 Backup failed

What i am doing wrong?

Image backups succeed on both clients.