Internal Server Error after upgrade to 7.8.3

I need immediate help! I Upgraded my Suite installation from 7.6 to 7.8.3 and now I’m stuck with Internal Server Error.
I double checked permissions and ownership.
I tried to use PHP V5.6 - 7.3.
There’s nothing to show when swtiching on display_error for php.
There’s nothing in the server logs.
Of course, I cleaned browser history after changing anything.
I had this problem mutliple times before but this time, it seems quite desperate.
Please help :frowning:

open config.php and make “log” level to “debug”.

If you fail to see any changes, I can quickly help you. Just PM me at skype in my signatures.

Don’t worry about cost.