After updating/upgrading your website it is often necessary to define some 301 redirects to make sure end users don't come across a broken link or a file not found error. While defining a 301 redirect in your .htaccess file or through the cPanel of your web host is not hard to do, it is easier just to download and enable the Path Redirect module. Drupal relies heavily on mod_rewrite and has a lot of rewriting rules defined so it is easy to get an infinite loop redirect when trying to edit the .htaccess file directly.