Pseudo parameter in cloudformation

Question

I'm using the below simple template and trying to list the region in parameter section using Pseudo parameter AWS::Region, however getting the below error while trying to update the stack :

Failed to retrieve external values

Image posted here [1]: https://i.sstatic.net/kUcoo.png

Nothing reporting on cloudtrail :

"responseElements": {
        "parameters": [
            {
                "parameterType": "List<AWS::Region>",
                "noEcho": false,
                "parameterKey": "S3"
            }

Below are my template details :

Parameters: 
 Region:
  Type: List<AWS::Region>
  Default: us-east-1

Resources:
###

Can someone give an advice. Thanks in advance.

Answer 1

Its not possible. You have to use CommaDelimitedList.