Dear Kier and Mike, I am developing an addon for XenForo and found the bug: I created new content type ( 'newtype' ) and one of its search constraints array ( 'states' ). In order to search result with certain 'states' I should try request Code: http://site.com/search/search?users=guiltar&type[newtype][states]=open but when nothing is found controller calls updateSessionActivity method which has code Code: $logParams = "$paramKey=" . urlencode($paramValue); This becomes error when $paramValue is an array: Code: urlencode() expects parameter 1 to be string, array given XenForo_Application::handlePhpError() urlencode() in XenForo/Model/User.php at line 868 I suggest to check if $paramValue is an array before calling urlencode(). Because the cannonical way to handle type specific constraints (via _handleInputType in search controller) leads to error. Thanks.