Error to be rectified in CloudFormation template

Question

My AWS CloudFormation template for Application load balancer is throwing this error: Failed to retrieve external values. Want help in rectifying this issue. I'm not sure where the error is occuring from. I'm guessing the error might be in the certificate parameter section or the tags, maybe the !Sub value is not taking in the value.

AWSTemplateFormatVersion: '2010-09-09'

Parameters:
  Name: 
    Description: Name of the project
    Type: String
  EnvironmentName: 
    Description: Environment of the Application Load balancer
    Type: String
  PublicSubnet:
    Description: Subnet for creating the Application Load balancer
    Type: List<AWS::EC2::Subnet::Id>
  Vpc:
    Description: VPC in which the resources are present
    Type: AWS::EC2::VPC::Id
  Certificate: 
    Description: Arn of the ssl certificate for HTTPS listener
    Type: AWS::CertificateManager::Certificate::Arn

Resources:
  SecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: ALB Security Group
      VpcId: !Ref Vpc
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: "80"
          ToPort: "80"
          CidrIp: "0.0.0.0/0"
        - IpProtocol: tcp
          FromPort: "443"
          ToPort: "443"
          CidrIp: "0.0.0.0/0"
      Tags:
        -
          Key: Name
          Value: !Sub ${EnvironmentName}-SG

  ApplicationLB:
    Type: 'AWS::ElasticLoadBalancingV2::LoadBalancer'
    Properties:
      IpAddressType: ipv4
      Name: Test-ALB
      Scheme: internet-facing 
      SecurityGroups:
        - !Ref SecurityGroup
      Subnets: !Ref PublicSubnet  
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName}-ALB
      Type: application
  HTTPSListener:
    Type: "AWS::ElasticLoadBalancingV2::Listener"
    Properties:
      LoadBalancerArn: !Ref ApplicationLB
      Port: 443
      Protocol: "HTTPS"
      SslPolicy: "ELBSecurityPolicy-2016-08"
      Certificates: 
        - 
          CertificateArn: !Ref Certificate
      DefaultActions: 
        - 
          Order: 1
          Type: "fixed-response"
          FixedResponseConfig:
            ContentType: "text/plain"
            MessageBody: "Please enter proper domain"
            StatusCode: "200"
  HTTPListener:
    Type: "AWS::ElasticLoadBalancingV2::Listener"
    Properties:
      LoadBalancerArn: !Ref ApplicationLB
      Port: 80
      Protocol: "HTTP"
      DefaultActions: 
        - 
          Order: 1
          RedirectConfig: 
            Protocol: "HTTPS"
            Port: "443"
            Host: "#{host}"
            Path: "/#{path}"
            Query: "#{query}"
            StatusCode: "HTTP_301"
          Type: "redirect"
  ALBTargetGroup:
    Type: 'AWS::ElasticLoadBalancingV2::TargetGroup'
    Properties:
      HealthCheckIntervalSeconds: 30
      HealthCheckTimeoutSeconds: 5
      HealthyThresholdCount: 3
      Port: 80
      Protocol: HTTP
      UnhealthyThresholdCount: 5
      VpcId: !Ref Vpc

Need clarification.

Answer 1

The error is related to the Type mentioned for the Certificate parameter.

Change it to String as below and pass certificate Arn as the value.

Certificate: 
    Description: Arn of the ssl certificate for HTTPS listener
    Type: String

Sample parameters.json file

[
  {
    "ParameterKey": "EnvironmentName",
    "ParameterValue": "dev"
  }, 
  {
    "ParameterKey": "Name",
    "ParameterValue": "stackoverflow"
  },
  {
    "ParameterKey": "Vpc",
    "ParameterValue": "vpc-0e104f6ad273a6648"
  },
  {
    "ParameterKey": "PublicSubnet",
    "ParameterValue": "subnet-0c2fc6571a7a6db2e, subnet-05a36fdef379c4fcd"
  },
  {
    "ParameterKey": "Certificate",
    "ParameterValue": "arn:aws:acm:us-east-1:111111111111:certificate/11ad06f1-b625-44b2-9797-4ecd81451af2"
  }

]