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
$logParams = "$paramKey=" . urlencode($paramValue);
urlencode() expects parameter 1 to be string, array given XenForo_Application::handlePhpError() urlencode() in XenForo/Model/User.php at line 868
Because the cannonical way to handle type specific constraints (via _handleInputType in search controller) leads to error.