Deploy failed when existing user pool triggered function is removed

I use existing user pool triggers like this.

    handler: handler.my_func
      - cognitoUserPool:
          pool: testpool
          trigger: PostAuthentication
          existing: true

However, when I remove one of them and deploy the process fails.
The error messages are

Failed to delete resource. User: arn:aws:sts::****:assumed-role/prjectname-IamRoleCustomResourcesLambdaEx-*****/prjectname-custom-resource-existing-cup is not authorized to perform: lambda:RemovePermission on resource

The version is 1.50.0

Probably some setting of iam is not enough.
Can this be solved by my definition in serverless.yml?
Please kindly advise.



Very similar, but I got this

Failed to create resource. User: arn:aws:sts::845110609621:assumed-role/propswap-jeanc-IamRoleCustomResourcesLambdaExecuti-1BXRS6XB57ESY/propswap-jeanc-custom-resource-existing-cup is not authorized to perform: iam:PassRole on resource: arn:aws:iam::845110609621:role/propsw3a762d80_sns-role-jeanc See details in CloudWatch Log: 2019/08/23/[$LATEST]5ad3be449c4f4e84a5835cdc4c5a2a53

With the following:

  timeout: 61
  handler: handlers/user/afterAuthenticate.js
    - cognitoUserPool:
        pool: ${file(amplify/custom.js):custom.user_pool_name}
        trigger: PostAuthentication
        existing: true

I’m getting a similar problem on 1.50.0.

Serverless Error ---------------------------------------
  An error occurred: PreSignUpCustomCognitoUserPool1 - Failed to create resource. User: arn:aws:sts::[num]:assumed-role/ttw3-cognito-triggers-liv-IamRoleCustomResourcesLa-9S662UBZG46B/ttw3-cognito-triggers-live2-custom-resource-existing-cup is not authorized to perform: iam:PassRole on resource: arn:aws:iam::[num]:role/[rol] See details in CloudWatch Log: 2019/08/24/[$LATEST]8062f5ca32e947f6a06a0e36a5284457.

handler: handler.autoConfirmUser
  - cognitoUserPool:
      pool: ${self:provider.environment.COGNITO_POOL}
      trigger: PreSignUp
      existing: true

Thank you for opening the issue!

I first mentioned that it happened when I removed a function, but as you say, another similar problem occurred when I deploy.
The problem occurred when I enabled Multi-Factor Authentication and provided a role to allow Amazon Cognito to send SMS messages.

Failed to create resource. User: arn:aws:sts::***:assumed-role/my-project-IamRoleCustomResourcesLambdaExecut-***/my-project-custom-resource-existing-cup is not authorized to perform: iam:PassRole on resource: arn:aws:iam::***:role/service-role/myUserPool-SMS-Role See details in CloudWatch Log: 2019/08/27/[$LATEST]***
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Having the same issue after removing a handler from the serverless.yml file that had an event referencing an existing cognito user pool. This occurs after deploying the handler function successfully, then removing the function handler definition (in its entirety) from the serverless.yml file and attempting to re-deploy.

An error occurred: CognitoCustomMessageHandlerCustomCognitoUserPool1 - Failed to delete resource. User: arn:aws:sts::ACCOUNTID:assumed-role/dev-opal-users-IamRoleCustomResourcesLambdaExecuti-18KXQ6A3U9B54/opal-users-dev-custom-resource-existing-cup is not authorized to perform: lambda:RemovePermission on resource: arn:aws:lambda:us-east-1:ACCOUNTID:function:opal-users-dev-cognitoCustomMessageHandler

If I check the offending IamRole, it does indeed have the correct permissions after deploying the functions. But when I remove the entire function from the serverless.yml file, I believe the opal-users-dev-custom-resource-existing-cup resource (created by the Serverless Framework) has it’s permissions removed BEFORE it attempts to do its work on the function handler that I removed (but fails since it no longer has permissions). Seems like an issue with order of operations, but no idea how to resolve.

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Eventually, now I deal with it by deleting the description below “event:” and manually linking triggers after deployment…

1 Like

Still getting the same/similar error in 1.61:

  Serverless Error ---------------------------------------
  An error occurred: CustomMessageCustomCognitoUserPool1 - Failed to create resource. Cannot read property 'Id' of null See details in CloudWatch Log: 2020/01/14/[$LATEST]cb27c13b56634f3e94ef038f6d268bbf.

with config:

    handler: handler.customMessage
    memorySize: 256
      - cognitoUserPool:
          pool: ${ssm:/cognitotriggers/${self:provider.stage}/user-pool-id~true}
          trigger: CustomMessage
          existing: true

@kizashitakata - I am doing the same thing for remediation - would be nice if it could be fixed properly.

I saw some users on the bug report thread deleted and re-created their user pool to “fix” it - this is not an option for me.

Also, fwiw, if I go to the url provided in the Serverless deploy output, the stack error says this:

Failed to delete resource. Statement cognitotriggers-dev-customMessage-us-west-2_*** is not found in resource policy. See details in CloudWatch Log: 2020/01/14/[$LATEST]cb27c13b56634f3e94ef038f6d268bbf

I am not able to locate the log mentioned…


I had this same issue (Serverless v2.43.1). What I wound up doing was this:

  1. Comment out the event in the lambda definition in serverless.yml
  2. Deploy
  3. Remove the lambda from serverless.yml
  4. Deploy
  5. Go to the AWS Console, and into your Cognito user pool. Navigate to the “Triggers” tab/page.
  6. Find your particular trigger and set the Lambda function to “None” (it was likely still showing the ARN of the lambda function you just deleted). Click the Save Changes button.