Reason : It may caused for php version of your widget calling or anything

Solution :  
Are you using an older version of php like 5.2 or 5.3 and trying to register an widget on somewhere?

Don’t write function directly in add_action()’s 2nd parameter. Write down the function name as string instead of the function itself. like add_action(‘after_setup_theme, ‘my_function_name’); function my_function_name() { } Also If your’e using php 5.2 then you have to register widget as “add_action(‘widgets_init’, create_function(”, ‘return register_widget(“My_Widget”);’) ); “