Question: It says that I can't change my Apple ID to my notification email
I was trying to change my Apple ID to my main email, which was set to a notification email at the time. When trying to change it, a message appeared stating that I couldn't set my notification email as my Apple ID. So, I removed it as my notification email and tried again, but the same message popped up. I am doing this on my Apple ID account page.
iPhone 6, iOS 11