AWS Cognito Error on Sign Up

I was exploring AWS Cognito for authentication. It works great, but I got the following error message after I tested the sign up process: An error was encountered with the requested page. I found out later that I misunderstood the AutoVerifiedAttributes field in my CloudFormation. I thought it would mark an email or phone number as verified without actually verifying them. Apparently, it means it will try to verify either email or phone number. So, when I set it to email, it sent a verification email and the sign up process went without error.