500 Internal Server Errors can be caused by many different issues.
Check your browser
Please be advised if you are using Internet Explorer as your browser, it is known to display an Internal Server Error when there isn’t one. Try using another browser first to eliminate this possibility.
If you are using a different Browser, then it may be due to one of the following: permissions / ownerships of files, memory usage, coding (.htaccess, premature end of script, software specific). The next step is to determine which of these is causing the error.
Check the memory
Log in to your server via SSH and run a top command, which will let you know if you have maxed-out your memory. If it is near full or you are unable to do this due to a ‘cannot allocate memory’ error, then you have likely found the issue.
To resolve a max memory issue the server will usually need to be rebooted, especially if there is not enough memory to log in or run commands.
Check the error logs
If memory is not the issue, then the next step is to take a look at your apache error log. On a Plesk server this log is located in: /etc/httpd/logs/
tail -f on the log to view the log as streaming, and then refresh the page giving you the 500 Error. Once you have refreshed the page end your tail command via
Take a look at the output of the log and it should give you more information about the error and what is causing it to occur.
Please note: ServInt has discontinued support for the Plesk control panel.
photo by Andy Melton