Fn::ImportValue does not match type {Array}

Question

I faced an issue with using the export and import functionality in CloudFormation. When I tried to import a value which actually is a list (array) I received the following error message "does not match type {Array}".

vpc.yaml (snippet)

PrivateSubnets:
  Description: A list of the private subnets
  Value: !Join [",", [!Ref PrivateSubnetOne, !Ref PrivateSubnetTwo]]
  Export:
    Name: !Join ["-", [!Ref "Environment", "PrivateSubnets"] ]

pipeline.yaml (snippet)

Subnets:
  Fn::ImportValue: !Sub "${Environment}-PrivateSubnets"

Error message:

    Property validation failure: [Value of property {/VpcConfig/Subnets} does not match type {Array}

Answer 1

This code resolved the issue;

Subnets: !Split 
   - ","
   - Fn::ImportValue: 
       !Sub "${Environment}-PrivateSubnets"