Question On One Form Two Models

I have followed this wiki:

and the actionCreate worked fine BUT the actionUpdate generates a PHP Fatal error: Call to a member function getErrors() on a non-object in yii\framework\web\helpers\CHtml.php

Could anyone please help as the wiki only discussed on actionCreate even though I know both share the view _form. Thank you!

Paste you actionUpdate() code.

Thank you jkofshy for your offer to help. I just figure out that one of my model was null, after fixing it worked as expected. Again, thank you very much!

No Problem