Invalid Access - You do not have permissions to view this page

[wolendranh]

Hi!

I had a question. I created app, and was able to grant access and receive refresh token for Account on which app was created(dev account I suppose).

But when I try to consent from seller account using "Login with Amazon button" I receive

"Invalid Access - You do not have permissions to view this page" instead of prompt with permissions that should be consented.
What can be the reason for such issue?

I found this post on Amazon Forums - https://sellercentral-europe.amazon.com/forums/t/mws-invalid-access-you-do-not-have-permissions-to-view-this-page/107950

Answer mentions that

Because my account was degraded to personal seller. Then I was told I can only view that page as a professional seller, it turned out that’s was true, all you need to do is to upgrade to professional seller.

Is seller required to have "professional seller" account to be able to consent to application?