Have a 500 error after migrating it from our development server to production. I zipped up the directory and copied SQL across manually. I am able to isolate the issue down to the theme because it works when I change the theme to another.
500 Internal Error says about some issue on the server and can be caused by different things. Anyway, to understand its nature you need to see your server error logs or enable PHP error display on the website. If you can’t do this, you need to contact your hosting provider for help in this question. Here is an article that may help you understand the error better http://www.wpbeginner.com/wp-tutorials/how-to-fix-the-internal-server-error-in-wordpress/
Very weird as I have a staging directory that is on the exact same server and it works just fine, when I put in to the Public_html folder it doesnt work.