Set group categories not working

Under the manage forms section on the administration menu, if you select 'Set Group Categories' it gives you the option to enter a category per line.

However, when you hit the submit button, it takes you to a blank page.

In the code it is sending it to here:

<form action="'.$CONFIG->wwwroot.'action/form/manage_form" method ="post" >

Where should it be going?

Form and related plugins

Form and related plugins

User-generated content, flexible user and group profiles, registration forms, custom file forms