Problem with seafdav.pid file

While doing research for another problem, I noticed these entries in controller.log which do occur every 10 seconds:

[07/30/16 10:01:50] seafile-controller.c(117): bad pidfile format: /opt/seafile/pids/seafdav.pid [07/30/16 10:01:50] seafile-controller.c(399): failed to read pidfile /opt/seafile/pids/seafdav.pid: Success

Looking in /opt/seafile/pids there is a file seafdav.pid but it’s size is 0.
What to do?

Thanks and best regards,
Jochen

Edit: Already mentioned here: forum.seafile.de

Edit2: Removed empty .pid-file and restarted seafile. Works now, new seafdav.pid file was created with pid inside. Anyway, since I don’t know how this happened, the controller should handle this normally.