500 Internal Server Error
If you see begin seeing 500 Internal Server Error responses from the server after you have created or edited an .htaccess file, the most likely cause of the problem is incorrect permissions and/or an error in the directive syntax.

• Permissions on the .htaccess file are not set correctly. Just like HTML and image files, the server must be able to read the .htaccess file. The simplest way to allow that is to make your .htaccess file readable by "other".

% pwd
/home/dh_xyz45/mycoolsite.com
% ls -l .htaccess
-rw-------   1 dh_xyz45  www         349 Nov 27 00:03 .htaccess
% chmod o+r .htaccess
% ls -l ~/mycoolsite.com/.htaccess
-rw----r--   1 dh_xyz45  www         349 Nov 27 00:03 .htaccess

• Syntax Error. An error in the syntax of a directive the .htaccess file will result in a 500 Internal Server Error. In addition, correct usage of a directive that is not allowed in the .htaccess file will result in a 500 status code. Whether or not a directive is allowed depends upon the server configuration file (httpd.conf; AllowOverride) and the directive itself.