Solution for Warning: Parameter 1 to modMainMenuHelper::buildXML() expected to be a reference

Warning: Parameter 1 to modMainMenuHelper::buildXML() expected to be a reference.

You will get this issue if the php version is upgraded in the server as joomla is not certified to work with PHP 5.3.0.


FIX: open the file
vi /home/<username>/public_html/modules/mod_mainmenu/helper.php
[replace <username> with your username]

Change
function buildXML(&$params)
to
function buildXML($params)