Your advice starting with smaller parts of the string failed too. So I assume your thinking of RegEx failing was right.
By accident I looked at the 1st line of my script and discoverd a fishy looking shebang (the exclamation mark/point was missing and a strange path). I discovered the path to perl with

After fixing the shebang with exclamation mark/point and the discovered path and implementing "quotemeta" I restarted the script successfuly. Thx for the ideas