title: AWS CloudFormation error with network interface
body: <p>I get this error whenever I launch my stack </p>
  
  <blockquote>
    <p>(Network interfaces and an instance-level security groups may not be
    specified on the same request (Service: AmazonEC2; Status Code: 400;
    Error Code: InvalidParameterCombination; Request ID:....))</p>
  </blockquote>
  
  <p>and the status in <code>Aws console</code> is: <code>ROLLBACK_COMPLETE</code></p>
  
  <p>How I can solve this error?</p>
  
  <pre><code>EC2Instance:
  Type: 'AWS::EC2::Instance'
  Properties:
    SecurityGroups: 
      - !Ref SecurityGroup
    KeyName : !Ref EC2Key
    AvailabilityZone: us-east-2a
    ImageId: ami-01410f0e8f8b1acca
    InstanceType: t2.micro
    NetworkInterfaces:
      - DeviceIndex: '0'
        SubnetId: !Ref PublicSubnet
  </code></pre>