Your comments

An answer would be nice.

Thanks
Is the generated JSON code even valid? I mean it ends with:

200 OK
}

What does the 200 OK here? If i try to import that file i will get:

Expecting , delimiter: line 64 column 1


# If i remove that 200 OK it works fine.
Well the problem was the "pattern" that you provided. You always need a pattern which only processed .php data thourgh the php-fpm, otherwise the above error occurs.
They say something like_ 

Access to the script '/srv/main/phpMyAdmin/themes/pmahomme/screen.png' has been denied (see security.limit_extensions)" while reading response header from upstream
The permisisons are: www-data:www-data

Is that wrong? This permisisons got automatically assigned from Ajenti
I just moved the phpmyadmin folder into the /srv/main directory and removed the custom path from the settings. Now I can access it, but the graphics won't load. They produce an "Access Denied" 

I can access it until i get to the /img directory, e.g.
http://XXX/phpMyAdmin/themes/pmahomme/ works
http://XXX/phpMyAdmin/themes/pmahomme/img - produces access denied

Why?
But i only get a "File not found." on a blank page :/
I have it like that:


Shouldn't that be right?
"You need to re-create your PMA content config under the "main" website" What do you mean with that? Do i still have 2 websites, or only the main?