[SOLVED]: Notice: Use of undefined constant DS – assumed ‘DS’ in

The DS constant has been removed in Joomla 3. If you really need it you can use DIRECTORY_SEPARATOR instead or insert the below code in your php file.

<?php
/* BEGIN: Define DS */
JLoader::import( "joomla.version" );
$version = new JVersion();
if (!version_compare( $version->RELEASE, "2.5", "<=")):
   if (!defined("DS")):
      define("DS", DIRECTORY_SEPARATOR);
   endif;
endif;
/* END: Define DS */
?>

Also there is a joomla plugin, named “DS Constant Plugin”, to fix this issue.