[SOLVED]: "Unknown mode: 117". Error creating empty image subvolume. UrBackup

Solution: UrBackup Server Web-Interface - Settings - Clients - your_buggy_client - Image Backups - Image backup file format - Change it!

In my case it turned out that I was using "Raw copy-on-write file" option with Windows client which is most likely not supported on Windows. I've set it to "Compressed VHDX (Compressed non-standard Virtual HardDisk v2) (beta)" and this made it work!

Example of logs:

(Server side, Web-Interface - Logs)

    Errors
    10/21/24 16:43
    Error creating empty image subvolume. "Unknown mode: 117"
    Errors
    10/21/24 16:43
    Error creating image backup destination.
    Errors
    10/21/24 16:43
    Backup failed

(Client side, C:\Program files\UrBackup\debug.log)

    0-1729518191-Basing image backup on last incremental or full image backup
    1-1729518191-Error retrieving last image backup. Doing full image backup instead.
    2-1729518191-Error creating empty image subvolume. "Unknown mode: 117"
    2-1729518191-Error creating image backup destination.
    0-1729518191-Time taken for backing up client buggy_client_hostname: 246ms
    2-1729518191-Backup failed