Ubuntu 20.04 LTS: Creating empty filesystem failed (Server error)

Hello Gurus,

since one year I use urbackup for my home network for 10 computers, half Linux, half Windows. Started on a RasPi2b with Ubuntu Server 18.04 LTS, updated two monthes ago to Ubuntu Server 20.04 LTS without any problem.
Once a month I have to restart the PasPi, caused by the unattended updates, which requires sometimes a reboot.
After last of such reboots at 17. Oct. i got for all clients the same error:
Creating empty filesystem failed (Server error) "ERROR: target path already exists: /backup/urbackup/<Client_Name>/201023-0800
Backup had an early error. Deleting partial backup.
The output of urbackup_snapshot_helper test is:
Testing for btrfs…
Create subvolume ‘/backup/urbackup/testA54hj5luZtlorr494/A’
Create a snapshot of ‘/backup/urbackup/testA54hj5luZtlorr494/A’ in ‘/backup/urbackup/testA54hj5luZtlorr494/B’
Delete subvolume (commit): ‘/backup/urbackup/testA54hj5luZtlorr494/A’
Delete subvolume (commit): ‘/backup/urbackup/testA54hj5luZtlorr494/B’

Tried ReInstallation: No change
Tried ReCompilation: No change

UrBackup Server is 2.4.13,
Urbackup clients are 2.4.8, 2.4.9 and 2.4.10.

More than 2000 backups are ok, now this.

Has anyone any hint for me, what change has happen through the unattended updates whithin the last month?

Thanks in advance.


I have the same problem. Would be very interested in a solution as well but I have no idea so far…


no, not really.
I set up a new server an step back to a ubuntu server 20.04 LTS from August, which runs urbackup without any problem and waiting for the next error after the next reboot…
Meanwhile I write down the open upgradelist to hopefully isolate the guilty package, see attachments.

2020-11-04_upgradelist.txt (10.3 KB) 2020-11-05_upgradelist.txt (6.1 KB) 2020-11-06_upgradelist.txt (6.0 KB) 2020-11-07_upgradelist.txt (6.0 KB)

Thank you for your update! I hope you will be able to track down the bad guy.

By the way: When I check the file system after a failed backup the folder is not there. Most times when I just retrigger the backup once from the server it seems to work flawlessly.

In fact: I just started a backup for client that was failing 3 times in a row from the server web frontend and the backup went through smoothly… Have you tried to start the backup from the server frontend?

Hello DrRSatzteil,

yes, I tried it several times, only from the web frontend, but never 3 times in series for the same client. Only one or two times for the same client, then I tried a different client.

Interesting: The full backups were ok. It concerned only the incremental backups.

Since the 04.11. the server was new set up, there was still two special behaviors:

Incremental Backup client 1 was ok on 05.11. (unscheduled),
Incremental Backup client 1 failed on 05.11. (unscheduled),
Incremental Backup client 1 was ok on 06.11. (scheduled),
Incremental Backup client 1 was ok on 07.11. (scheduled),
Incremental Backup client 1 was ok on 08.11. (scheduled).

Full backup on client 2 was started ok on 04.11. (scheduled), Client went offline,
Full backup on client 2 was continued and ok on 04.11. (scheduled), Client went offline,
Full backup on client 2 was continued and failed on 05.11. (scheduled), Client went offline,
Full backup on client 2 was finished and ok on 06.11. (scheduled).


Sorry I didn’t express myself clearly: the client had three failed automatic/scheduled backup attempts when I triggered it manually from web frontend. So it appeared to me as if there was something different when I trigger the backup manually compared to a scheduled backup.

Well… it didn’t work for another failing client so I guess that this was coincidence. However I can confirm that full backups are working fine.

Hello All,

what should I say: The new setup solved the error.

Thread closed.

Thanks to all.