Seafile 6.3.9 Webdav defect on Red Hat Enterprise Linux 7 / CentOS 7

Hello, having upgraded to 6.3.9 Webdav does not start:

[12/19/18 07:55:14] seafile-controller.c(592): pid file /opt/seafile/pids/seafevents.pid does not exist
[12/19/18 07:55:14] seafile-controller.c(623): seafevents need restart…
[12/19/18 07:55:14] seafile-controller.c(88): spawn_process: /usr/bin/python2.7 -m seafevents.main --config-file /opt/seafile/conf/seafevents.conf --logfile /opt/seafile/logs/seafevents.log -P /opt/seafile/pids/seafevents.pid
[12/19/18 07:55:14] seafile-controller.c(103): spawned /usr/bin/python2.7, pid 8825
[12/19/18 07:55:14] seafile-controller.c(592): pid file /opt/seafile/pids/seafdav.pid does not exist
[12/19/18 07:55:14] seafile-controller.c(629): seafdav need restart…
[12/19/18 07:55:14] seafile-controller.c(88): spawn_process: /usr/bin/python2.7 -m wsgidav.server.run_server --log-file /opt/seafile/logs/seafdav.log --pid /opt/seafile/pids/seafdav.pid --port 8080 --host 0.0.0.0
[12/19/18 07:55:14] seafile-controller.c(103): spawned /usr/bin/python2.7, pid 8826
[12/19/18 07:55:24] seafile-controller.c(592): pid file /opt/seafile/pids/seafevents.pid does not exist
[12/19/18 07:55:24] seafile-controller.c(623): seafevents need restart…
[12/19/18 07:55:24] seafile-controller.c(88): spawn_process: /usr/bin/python2.7 -m seafevents.main --config-file /opt/seafile/conf/seafevents.conf --logfile /opt/seafile/logs/seafevents.log -P /opt/seafile/pids/seafevents.pid
[12/19/18 07:55:24] seafile-controller.c(103): spawned /usr/bin/python2.7, pid 8900
[12/19/18 07:55:24] seafile-controller.c(592): pid file /opt/seafile/pids/seafdav.pid does not exist
[12/19/18 07:55:24] seafile-controller.c(629): seafdav need restart…

Even disabling webdav did not make seafile useable.

We use Seafile in connection with Shibboleth Authentication.
This works perfectly with Version seafile-pro-server-6.3.6 .

Any ideas and help is highly appreciated.

Best regards
Thomas