Sidebar not showing on index.php

After upgrading from 2.2 to 2.2.1 the sidebar isn’t showing anymore on my index.php. On all my other sites it works fine. Maybe there is a problem with the permalinks because the sourcecode says: Fatal error</b>: Call to undefined function: stripos() in <b>/home/www/web4120/html/loudpeople/wp-includes/link-template.php</b> on line <b>446</b>

URL of the blog with the error