Wow, how do you know so many stuff? 
Now the server works! – No performance issues, @InvisibleMan78 
The change I want to test is about Cover Arts, I cannot find a release with Cover Arts, though.
Do you know one? Or a way to search for one?
Or maybe none are included in the sample data…
I found a release with Add cover art edit in its history but the Cover Art tab is empty, despite the cover showing OK in the edit history.
There must be a way to test CAA tab code in development local MBS, no?
Is it the same problem as Do[es] not download the covers from picard with a development server, maybe?