Template error: Fn::Select cannot select nonexistent value at index 1

[#1]

Just going through the AWSQuickstart guide https://docs.aws.amazon.com/quickstart/latest/cloudera/step2.html to create an EDH. The CloudFormation stack creation is failing with:

"Template error: Fn::Select cannot select nonexistent value at index 1"

I have left the template and S3 details as the defaults.

[#2]

This error may have been due to only specifying one availability zone. Since using two, I get further but with different errors. I'll continue to experiment...