If you continue to get this message, you need to read this line of the error message:
More information about this error may be available in the server error log
That tells you what you need to do. The 500 error is way to generitc fo ranyone here ot be able to give you any idea of what it is. You should have access to the error logs on your site. Depending on the hosting platform you will find them in your ocntorl panel, or sometimes in the sites folders in files called error_log. Read through those when you find the errors and pinpoint exactly what error is happening where.
