You have posted this thread in the wrong location, I will move it for you.
Please mark the appropriate replies as CORRECT / HELPFUL so our team and other members know that your question(s) has been answered to your satisfaction.
the reason why you get this error is because the user that is accessing the Qlik Sense application (embedded via IFrame) does not have a token assigned from within the management console of the Qlik Server where the accessed document can be found.
I believe this answers your question. Please mark this as correct and helpful to indicate this has been answered.
