Hello @kpecar!

What question type are you using? I tried using both request response and custom validation and I receiver no error. 

Hello @kpecar , If you have added request response and Custom Validation then it will act only for Custom Validation as it checks for the condition first which you might have added so the Request Response gets neglected as that is only shown if person is skipping the question.

I am aware from several posts  that @TomG has reported that custom validation has no impact on Request Response. This is what I have experienced with my side by side question. I am wanting to request responses when only some question/s has been unanswered  (in the case below rows 2-5 in column 2) therefore this would need custom validations.

@kpecar  You can have a custom validation as shown in below image. The additional comments column would be optional to answer but the scales would need to be answered.