I found out that it works best with the following line of code that might has to be changed in the /config.php, admin/install.php & /admin/edit_config.php
‘error_reporting(0);’ instead of
‘error_reporting(E_ALL & ~E_NOTICE);’
No more messages/warnings/… are showing up so far so my first issue is fixed right now.
Btw I currently have another issue. Please have a look at my new forum topic (Installation/SQL Syntax Error).