Imposible to know. The 500 error message is a generic catch all error. Some hosts will just show the generic error message when any error occurs rather than show the actual error message.
we need to know what the real error behind the generic message is in order to troubleshoot.
The following code may turn error reporting on, add it at line 1:
If that doesn't show the real error, you will need to contact the host to have them look in the error logs.
once we know what the error is, we will be able to troubleshoot the cause.