This is the log from :
/var/log/plesk/panel.log
stderr:
filemng: Error occurred during /usr/bin/base64 command.
[2019-12-08 19:51:57.427] ERR [panel] Task failed: id=61, pid=18261, type=ext-kolab-task_install, error=filemng failed: filemng: Error occurred during /usr/bin/base64 command...