Hi,
please see:
when getting an internal server error (this logfiles are also asked in the template shown when creating a new thread.
This doesn't match your initial statement:
Wild guessing as you havn't filled out the shown template:
You're running PHP7 on this Ubuntu 16.04 and ownCloud 9.0.1. However this version of ownCloud is not compatible with PHP7 (you need 9.1.0 or 9.0.3)