Form API Error - illegal selection | Drupal 8

Form API Error - illegal selection

Submitted by editor on Tue, 12/08/2015 - 11:38

I have following message, What can I do ?
 An illegal choice has been detected. Please contact the site administrator.

Most likely, this error is due to dynamicaly changed options list.

If you want to change the values of the options list, You must add:
'#validated' => TRUE

Add new comment

This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Enter the characters shown in the image.