Adding a second authorizer of type COGNITO_USER_POOL fails

I’m relatively new to the serverless framework. I want to grant access to my endpoints via a cognito user pool. I’ve created the user pool in the AWS console directly. I then deployed my function for the corresponding end point and added the authorizer in the console too.

Afterwards I’ve added the following authorizer snippet to my serverless.yml file:

functions:
  test1:
    handler: handler.test1
    events:
      - http:
          path: /test1
          method: post 
          integration: lambda
          request:
            template:
              application/json: "$input.json('$')"
          response:
            headers:
              Content-Type: "'application/json'"
          authorizer:
            arn: arn:YYYYYYYYYY:XXXXXXXXXXXXXXXX

It looks like my end point is still working correctly, using the cognito pool for access. I then added a second endpoint where I wanted to define everything in the serverless.yml in the first place. So I’ve added this snippet to the function section

  test2:
    handler: handler.test2
    events:
      - http:
          path: /test2
          method: post 
          integration: lambda
          request:
            template:
              application/json: "$input.json('$')"
          response:
            headers:
              Content-Type: "'application/json'"
          authorizer:
            arn: arn:YYYYYYYYYY:XXXXXXXXXXXXXXXX

Using the same user pool arn as for method test1. However, this result in an error when I try to deploy:

An error occurred: ApiGatewayMethodTest2Post - Invalid authorizer ID specified. Setting the authorization type to CUSTOM or COGNIT_USER_POOLS requires a valid authorizer.

Now I’m asking myself two questions:

  1. Why isn’t it working for test2

  2. How to use existing user pool for granting access to gateway endpoints?