Systemd service stop failed


I’m running Ubuntu 18.04 and Seafile Server CE 7.1.3. I have a strange error when I stop seahub.service via systemd by executing sudo service seahub stop. The Seahub is actually stopped, but sudo service seahub status states that it failed to do so. Below is the listing of status. I didn’t see this error before. Did anyone encounter this problem before?

And, besides, what is the warning looking for plugins in '/usr/lib64/sasl2' ... failed to open directory? My system does not have this directory at all.

● seahub.service - Seafile hub
   Loaded: loaded (/etc/systemd/system/seahub.service; enabled; vendor preset: enabled)
   Active: failed (Result: signal) since Thu 2020-05-07 23:38:03 MSK; 2s ago
  Process: 13904 ExecStop=/home/seafile/seafile-server-latest/ stop (code=exited, status=0/SUCCESS)
  Process: 13418 ExecStart=/home/seafile/seafile-server-latest/ start (code=exited, status=0/SUCCESS)
 Main PID: 13441 (code=killed, signal=KILL)

May 07 23:23:27 hostname python3[13441]: looking for plugins in '/usr/lib64/sasl2', failed to open directory, error: No such file or directory
May 07 23:23:32 hostname[13418]: Seahub is started
May 07 23:23:32 hostname[13418]: Done.
May 07 23:23:32 hostname systemd[1]: Started Seafile hub.
May 07 23:38:02 hostname systemd[1]: Stopping Seafile hub...
May 07 23:38:02 hostname[13904]: Stopping seahub ...
May 07 23:38:02 hostname systemd[1]: seahub.service: Main process exited, code=killed, status=9/KILL
May 07 23:38:03 hostname[13904]: Done.
May 07 23:38:03 hostname systemd[1]: seahub.service: Failed with result 'signal'.
May 07 23:38:03 hostname systemd[1]: Stopped Seafile hub.