Interference with an .htaccess file
If you have implemented .htaccess on your site, it may be interfering with the web page you are trying to load into your browser. Please double check the .htaccess configurations to ensure that it doesn’t contain any errors.To confirm whether a misconfiguration .htaccess is the cause of the 500 Internal Server error, either remove or rename the .htaccess file temporarily and then try to reload the page. Source netfirms.com
