Following the update to WP 3.9.1 and MySQL I am getting the following error on a site:
Strict Standards: call_user_func_array() expects parameter 1 to be a valid callback, non-static method dc_jqverticalmegamenu::header() should not be called statically in /home/xyzsite/public_html/wp-includes/plugin.php on line 470
The reference is to this plugin. A quick search shows about 82 pages out there with the same error, but no reference to a solution. I would appreciate some guidance on resolving this.