PHP警告：为foreach（） - gantry插件提供的参数无效

I got this error log few days ago

PHP Warning:  Invalid argument supplied for foreach() in /home/karatm/public_html/wp-content/plugins/gantry/bugfixes.php on line 52<br>
PHP Warning:  Invalid argument supplied for foreach() in /home/karatm/public_html/wp-content/plugins/gantry/bugfixes.php on line 52<br>
PHP Warning:  Invalid argument supplied for foreach() in /home/karatm/public_html/wp-content/plugins/gantry/bugfixes.php on line 102<br>

This is line 52 from bugfixes.php:

foreach($sidebar_contents as $sidebar_contents_id => &$sidebar_widget_instance)

This is line 102 from bugfixes.php:

foreach ($override_sidebar as $position => &$sbw_instances)

What this error mean, how can i fix this ?

(if someone can help me, i can send him the full .php file)

Thanks

foreach ($override_sidebar as $position => &$sbw_instances) try to remove & try this foreach ($override_sidebar as $position => $sbw_instances)