Oops, Something Went Wrong (Internal Server Error)

I am getting this error, Oops, something went wrong (Internal Server Error) when trying to add anything to the cart.

The only thing that changed recently is the php version, from 5.6 to 7.1

Are there settings i need to change?

I edited config.php and set debug to true. I'm not seeing any info though, where should i see it?

Any help is greatly appreciated.

Never mind, thank you. I have discovered that an add on has stopped working. No changes were made to it so it must be php related. I disabled the add on and it's working.

Hello

Did you try development mode ?

In config.local.php set

ini_set('display_errors', 1);

and in file config.php please find "DEVEL" and replace

//define('DEVELOPMENT', true);

on

define('DEVELOPMENT', true);

Best regards

Robert