Buying PHP sites not working except WordPress

Hello.
I moved some sites from a server to another. The php version in the new server is 7.0 while the one in the old server is 5.4
Sites work fine on old server but they don't work on the new server. They show HTTP ERROR 500
There is a WordPress site in the new server and this one is working fine. Only the custom php sites are not working.
New server is on ubuntu 16.04 if that matters.
Need some help to get the sites working.
If you have experience in solving such problems, send me a message.
Thanks.

 

If you get error 500 there must be a log that explains whats going on. In most cases are file permitions.

 

Odds are the scripts that were running the older version are calling functions that do not exist in the new version PHP. As suggested above, check the error logs for direction. If you are running a control panel on the server, you may have the option of selecting to use a different version of PHP (perhaps even 5.4) for the sites that are not working as well.

Chris

 

Thanks for your help guys.
There's no cpanel. Just lamp stack in ubuntu.
I know about the error log and I checked it, but I can't get past the errors then.
Perhaps one of you can take a look at it?

 

Your problem can be anything. It can be as simple as a single function that is deprecated with PHP 7 to needing complete re-writes of entire functions / files to fit the new PHP version.

It's usually recommened to simply use PHP 5 with your PHP 5 scripts and use PHP 7 with your PHP 7 scripts. Otherwise your only alternative is to have someone go trough the code, and "upgrade" it to support PHP 7 (And most likely no longer support PHP 5, unless you specifically want and ask for it)-

 

try to downgrade to php5.4