If you are receiving a 500 Internal Server error, it is usually due to one of the following:
1) Some code in your .htaccess file is incorrect
Try renaming your .htaccess to htaccess.old If you no longer receive the error, you can fix the code and rename back to .htaccess
2) Your folder and/or file permissions are incorrect or set too high
Since we use suPHP, you need to make sure your folders permissions are set at 755 and your files are set at 644.
3) Your PHP version is too high for your script or plugin.
We use PHP 5.6+ on our servers and due to changes from 5.2 to 5.3 some older code designed for 5.2 will not work on 5.3+, so you may need to update any older scripts.
4) If you are exceeding your accounts memory limit or processes limit, 500 or 503 errors can occur.
You can view your resource usage in cPanel under Metrics --> CPU and Concurrent Connection Usage
5) Some incorrect PHP code in your pages.
Check the file "error_log" in the corresponding folder for any PHP errors.