title: AWS cloudformation - Stack exists but with non-updatable status: ROLLBACK_COMPLETE
body: <p>I'm following this tutorial: <a href="https://github.com/awslabs/codepipeline-nested-cfn" rel="nofollow noreferrer">https://github.com/awslabs/codepipeline-nested-cfn</a>
  and running into this error after running the following command: </p>
  
  <pre><code>aws cloudformation create-stack --stack-name NestedCFN-CodePipeline --template-body file://codepipeline-cfn-codebuild.yml --parameters file://codepipeline-cfn-codebuild.json --capabilities CAPABILITY_NAMED_IAM
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/F9uf9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/F9uf9.png" alt="enter image description here"></a></p>
  
  <p>Does anyone have any idea why? </p>
  
  <p>I deleted all stacks and started from a clean slate and the cloudformation stack gets to this part and fails with the error below:</p>
  
  <p><a href="https://i.stack.imgur.com/bolzN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bolzN.png" alt="enter image description here"></a></p>
  
  <p>Here's my config-prod.json; everything is similar to this repo except I changed the amiID: <a href="https://github.com/awslabs/codepipeline-nested-cfn" rel="nofollow noreferrer">https://github.com/awslabs/codepipeline-nested-cfn</a></p>
  
  <pre><code>{  
     "Parameters":{  
        "TemplatePath":"TEMPLATE_PATH_PLACEHOLDER",
        "VPCID":"vpc-4d08af25",
        "PrivateSubnet1":"subnet-a2e74bca",
        "PrivateSubnet2":"subnet-3d21c647",
        "PublicSubnet1":"subnet-69e44801",
        "PublicSubnet2":"subnet-c726c1bd",
        "S3BucketName":"nestedcfnbasestack-s3bucket-uvh827b8uyjw",
        "KeyPair":"testKeyName",
        "AMIId":"ami-f63b1193",
        "WebInstanceType":"t2.large",
        "WebMinSize":"1",
        "WebMaxSize":"2",
        "DBSubnetGroup":"nestedcfnbasestack-rdssubnetgroup-q0th4tfkt4m8",
        "DBUsername":"dbadmin",
        "DBPassword":"dbpAssw0rd",
        "DBInstanceType":"db.t2.small",
        "Environment":"prod"
     }
  }
  </code></pre>