intellisence

THE SOLUTION

Add this line of code

public function get_columns(){}

after the last closing bracket “}” in the following two files:

1. /wp-content/plugins/gravityforms/notification.php
2. /wp-content/plugins/gravityforms/form_settings.php

Basically, when you extend the WP_List_Table class, you must override by at least defining the get_columns() method/function in the sub-class.

In the following example, the My_New_Class class extends the WP_List_Table class which now makes it a sub-class of WP_List_Table. WordPress requires sub-classes of WP_List_Table to override the get_columns() method/function – so we must define it in our sub-class.

class My_New_Class extends WP_List_Table {
...
public function get_columns(){}
...
}