Repository - file won't accept changes

Hi all,
using Repository of @Jannis quite a lot, all working fine. Until now.

I got this message, changes don’t work.
Anybody with ideas, help?

Anything special about that file?

PHP error log?

Maybe cross site scripting filters of the hoster?

Thanks Jannis.
Normal csv file, very small.
no cross scripting filters afaik
How do I get the PHP error log?

Ask your hosting company.