Ok I think my problem is caused by internal server errors.
I have downloaded ownCloud-2.6.0.9963-daily20180705-setup and installed it. but it still restarts the scanning without loading new files to the server. I notice it stops at an internal server error and restarts again.
I have asked in another post for help on that. Internal server error (500) - #9 by DeepDiver1975
will keep you posted.