Preview works but Submit not, get Error 500

Getting Crazy, installed brandnew the guestbook. Preview works but Submit does'nt. Have no idea what to do, maybe someone can check and tell me what to change that it works?

If someone is so nice take a look at guestbook.roofrunners.de

Thanks in advanced.

Marco

maybe rights not correct? still:

Diese Seite funktioniert nicht
guestbook.roofrunners.de kann diese Anfrage momentan nicht verarbeiten.
HTTP ERROR 500

public and temp is set to 777

Very Easy, with PHP 7.1 it does not work, changed to 7.0 and everything is fine.

I've not worked with the guestbook for years but even the latest version is over a decade old so I'm guessing PHP 7.1 has removed some old functions that AG uses.

Economics is one of the most difficult subject which is often is faced by students during their college time. They often spend a lot time trying to complete these assignments. To ensure that students get good marks in their assignments, we at Assignment Help provide Economics Assignment Help to students all over the world. We are the best online economics assignment help providers for the last 5 years