Actually scratch everything, I've deleted both log files, restarted the services, and got fresh files with current data:
seafile.log
[08/16/23 16:16:01] socket file exists, delete it anyway
[08/16/23 16:16:02] http-server.c(181): fileserver: worker_threads = 10
[08/16/23 16:16:02] http-server.c(196): fileserver: fixed_block_size = 8388608
[08/16/23 16:16:02] http-server.c(211): fileserver: web_token_expire_time = 3600
[08/16/23 16:16:02] http-server.c(226): fileserver: max_indexing_threads = 1
[08/16/23 16:16:02] http-server.c(241): fileserver: max_index_processing_threads= 3
[08/16/23 16:16:02] http-server.c(263): fileserver: cluster_shared_temp_file_mode = 600
seahub.log is actually empty. I have no idea why it suddenly stopped working.
I've rechecked the services, and altough Plesk states it's running, I couldn't find the proper running process. Instead via htop I found a bunch of seafile server processes associated to domains, that do not even have Plesk Premium Email active, let alone seafile. Something seems to be going horribly wrong somewhere.
I could find a running seafile and seahub service for our own domain with the latest output being:
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262742]: Stopping seahub ...
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 36084 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 36090 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 36091 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 36092 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 36093 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 36094 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 261954 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 262101 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 262106 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 262110 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 262115 failed: Operation not permitted
Aug 16 16:12:00 SERVER.DOMAIN.TLD seahub.sh[262746]: pkill: killing pid 262116 failed: Operation not permitted
Aug 16 16:12:01 SERVER.DOMAIN.TLD seahub.sh[262742]: Failed to stop seahub.
Aug 16 16:12:05 SERVER.DOMAIN.TLD seahub.sh[262817]: LC_ALL is not set in ENV, set to en_US.UTF-8
Aug 16 16:12:05 SERVER.DOMAIN.TLD seahub.sh[262817]: Starting seahub at port 8001 ...
Aug 16 16:12:10 SERVER.DOMAIN.TLD seahub.sh[262817]: Seahub is started
Aug 16 16:12:10 SERVER.DOMAIN.TLD seahub.sh[262817]: Done.
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[264992]: Stopping seahub ...
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 36084 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 36090 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 36091 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 36092 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 36093 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 36094 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 263855 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 263860 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 263861 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 263862 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 263863 failed: Operation not permitted
Aug 16 16:14:49 SERVER.DOMAIN.TLD seahub.sh[265023]: pkill: killing pid 263864 failed: Operation not permitted
Aug 16 16:14:50 SERVER.DOMAIN.TLD seahub.sh[264992]: Done.
Aug 16 16:21:11 SERVER.DOMAIN.TLD seahub.sh[15966]: LC_ALL is not set in ENV, set to en_US.UTF-8
Aug 16 16:21:11 SERVER.DOMAIN.TLD seahub.sh[15966]: Starting seahub at port 8001 ...
Aug 16 16:21:16 SERVER.DOMAIN.TLD seahub.sh[15966]: Seahub is started
Aug 16 16:21:16 SERVER.DOMAIN.TLD seahub.sh[15966]: Done.
At the same time I managed to find the service, that isn't running, from my customer that is complaining:
root@server:/var/www/vhosts/DOMAIN.TLD/logs# systemctl status seahub@8106.service
● seahub@8106.service - Seafile hub
Loaded: loaded (/etc/systemd/system/seahub@8106.service; enabled; vendor preset: enabled)
Active: failed (Result: signal) since Wed 2023-08-16 16:26:22 CEST; 5min ago
Process: 16774 ExecStart=/var/www/vhosts/DOMAIN.TLD/seafile/seafile-server-latest/seahub.sh start 8106 (code=exited, status=0/SUCCESS)
Process: 18468 ExecStop=/var/www/vhosts/DOMAIN.TLD/seafile/seafile-server-latest/seahub.sh stop (code=exited, status=1/FAILURE)
Main PID: 16805 (code=killed, signal=KILL)
Aug 16 16:26:20 SERVER.DOMAIN.TLD seahub.sh[18488]: pkill: killing pid 15983 failed: Operation not permitted
Aug 16 16:26:20 SERVER.DOMAIN.TLD seahub.sh[18488]: pkill: killing pid 15984 failed: Operation not permitted
Aug 16 16:26:20 SERVER.DOMAIN.TLD seahub.sh[18488]: pkill: killing pid 15985 failed: Operation not permitted
Aug 16 16:26:20 SERVER.DOMAIN.TLD seahub.sh[18488]: pkill: killing pid 15986 failed: Operation not permitted
Aug 16 16:26:20 SERVER.DOMAIN.TLD seahub.sh[18488]: pkill: killing pid 15987 failed: Operation not permitted
Aug 16 16:26:22 SERVER.DOMAIN.TLD seahub.sh[18468]: Failed to stop seahub.
Aug 14 09:04:41 SERVER.DOMAIN.TLD systemd[1]: Stopping Seafile hub...
Aug 14 09:04:41 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Main process exited, code=killed, status=9/KILL
Aug 14 09:04:47 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Failed with result 'signal'.
Aug 14 09:04:47 SERVER.DOMAIN.TLD systemd[1]: Stopped Seafile hub.
Aug 16 13:52:27 SERVER.DOMAIN.TLD systemd[1]: Starting Seafile hub...
Aug 16 13:52:32 SERVER.DOMAIN.TLD systemd[1]: Started Seafile hub.
Aug 16 16:09:36 SERVER.DOMAIN.TLD systemd[1]: Stopping Seafile hub...
Aug 16 16:09:36 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Main process exited, code=killed, status=9/KILL
Aug 16 16:09:37 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Control process exited, code=exited, status=1/FAILURE
Aug 16 16:09:37 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Failed with result 'signal'.
Aug 16 16:09:37 SERVER.DOMAIN.TLD systemd[1]: Stopped Seafile hub.
Aug 16 16:09:41 SERVER.DOMAIN.TLD systemd[1]: Starting Seafile hub...
Aug 16 16:09:46 SERVER.DOMAIN.TLD systemd[1]: Started Seafile hub.
Aug 16 16:10:25 SERVER.DOMAIN.TLD systemd[1]: Stopping Seafile hub...
Aug 16 16:10:25 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Main process exited, code=killed, status=9/KILL
Aug 16 16:10:26 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Control process exited, code=exited, status=1/FAILURE
Aug 16 16:10:26 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Failed with result 'signal'.
Aug 16 16:10:26 SERVER.DOMAIN.TLD systemd[1]: Stopped Seafile hub.
Aug 16 16:10:30 SERVER.DOMAIN.TLD systemd[1]: Starting Seafile hub...
Aug 16 16:10:36 SERVER.DOMAIN.TLD systemd[1]: Started Seafile hub.
Aug 16 16:12:32 SERVER.DOMAIN.TLD systemd[1]: Stopping Seafile hub...
Aug 16 16:12:32 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Main process exited, code=killed, status=9/KILL
Aug 16 16:12:33 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Control process exited, code=exited, status=1/FAILURE
Aug 16 16:12:33 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Failed with result 'signal'.
Aug 16 16:12:33 SERVER.DOMAIN.TLD systemd[1]: Stopped Seafile hub.
Aug 16 16:12:33 SERVER.DOMAIN.TLD systemd[1]: Starting Seafile hub...
Aug 16 16:12:38 SERVER.DOMAIN.TLD systemd[1]: Started Seafile hub.
Aug 16 16:14:48 SERVER.DOMAIN.TLD systemd[1]: Stopping Seafile hub...
Aug 16 16:14:56 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Main process exited, code=killed, status=9/KILL
Aug 16 16:14:57 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Failed with result 'signal'.
Aug 16 16:14:57 SERVER.DOMAIN.TLD systemd[1]: Stopped Seafile hub.
Aug 16 16:22:27 SERVER.DOMAIN.TLD systemd[1]: Starting Seafile hub...
Aug 16 16:22:33 SERVER.DOMAIN.TLD systemd[1]: Started Seafile hub.
Aug 16 16:26:20 SERVER.DOMAIN.TLD systemd[1]: Stopping Seafile hub...
Aug 16 16:26:20 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Main process exited, code=killed, status=9/KILL
Aug 16 16:26:22 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Control process exited, code=exited, status=1/FAILURE
Aug 16 16:26:22 SERVER.DOMAIN.TLD systemd[1]: seahub@8106.service: Failed with result 'signal'.
Aug 16 16:26:22 SERVER.DOMAIN.TLD systemd[1]: Stopped Seafile hub.
I have absolutely no clue what is going on all of the sudden...