Backup failed BASE_DIR_LOST


Hi, I’m running urbackup client on a linux machine but I get some errors while performing a backup.
I read the faq about this error but it primarily refers to windows.

Here are some logs:
2018-10-12 05:27:28(info): Starting scheduled incremental file backup…
2018-10-12 05:27:33(warning): Restarting shadow copy of / because it was started by this server
2018-10-12 05:27:33(info): Snapshot is not mounted. Already removed
2018-10-12 05:27:33(info): LVM snapshot still exists. Destroying LVM snapshot /dev/mapper/pastificio–vg-urbackup_snap_305c623f899b3e57372e60a1faad209e93e4a940c68401ec…
2018-10-12 05:27:33(info): Logical volume “urbackup_snap_305c623f899b3e57372e60a1faad209e93e4a940c68401ec” successfully removed
2018-10-12 05:27:33(info): Using default stripesize 64.00 KiB.
2018-10-12 05:27:33(info): Logical volume “urbackup_snap_6d77a495b40a1420832d2618627c0992c3795e6d72022306” created.

And at the end:

2018-10-12 05:27:33(info): Indexing of "pastificio" done. 3368 filesystem lookups 0 db lookups and 1 db updates
2018-10-12 05:27:33(info): Backing up ".symlink_snapd.refresh.timer" without snapshot.
2018-10-12 05:27:33(info): agenda: Loading file list...
2018-10-12 05:27:33(info): agenda: Calculating file tree differences...
2018-10-12 05:27:34(info): agenda: Indexing file entries from last backup...
2018-10-12 05:27:34(info): agenda: Calculating tree difference size...
2018-10-12 05:27:34(info): agenda: Linking unchanged and loading new files...
2018-10-12 05:48:00(error): Error getting file patch for "SVOBm6SNMAmoheW0ErIs|pastificio/pastificio/env/lib/python2.7/site-packages/django/contrib/auth/" from agenda. Errorcode: BASE_DIR_LOST (7)
2018-10-12 05:48:00(info): Hint: Current root backup path does not exist anymore. Usually this is because the current file system snapshot it was backing up was deleted because it ran out of snapshot storage space. See for details and for how to fix this issue
2018-10-12 05:48:00(info): Saving incomplete file. (2)
2018-10-12 05:48:00(error): Client agenda went offline.
2018-10-12 05:50:16(info): Waiting for file transfers...
2018-10-12 05:50:19(info): Waiting for file hashing and copying threads...
2018-10-12 05:50:21(info): Waiting for metadata download stream to finish
2018-10-12 05:50:21(info): Writing new file list...
2018-10-12 05:50:22(info): Number of copied file entries from last backup is 4151
2018-10-12 05:50:29(info): Transferred 537.046 KB - Average speed: 3.584 KBit/s
2018-10-12 05:50:29(info): (Before compression: 1.9475 MB ratio: 3.71335)
2018-10-12 05:50:29(info): 115.585 MB of files were already present on the server and did not need to be transferred
2018-10-12 05:50:29(info): Time taken for backing up client agenda: 23m 1s
2018-10-12 05:50:29(error): Backup failed

The disk has plenty of space. This is the output of df -ah

sysfs                               0     0     0    - /sys
proc                                0     0     0    - /proc
udev                             3,9G     0  3,9G   0% /dev
devpts                              0     0     0    - /dev/pts
tmpfs                            787M  804K  786M   1% /run
/dev/mapper/pastificio--vg-root  219G  4,5G  203G   3% /
securityfs                          0     0     0    - /sys/kernel/security
tmpfs                            3,9G     0  3,9G   0% /dev/shm

Do you have any hint that could help me performing my backup?