AWS API Gateway: error Invalid mapping expression parameter specified: method.response.header.access-control-allow-origin

Question

For the first time in the last years with AWS API Gateway I got this strange blocking error, that can kills production environment: in one day many of my responses (not all) lost their Access-Control-Allow-Origin header. In web UI I also see that they are not exists. But they are still exists in exported Swagger file. And more than that - I cannot set any value, for '*' or 'https://example.com' I am getting error:

Invalid mapping expression specified: Validation Result: warnings : [], errors : [Invalid mapping expression parameter specified: method.response.header.access-control-allow-origin]

This is from yesterday (I did not change anything to get this defect), looks like horrible bug of AWS that blocks our development (main product is no longer available without CORS headers). And now I am afraid to use AWS API Gateway for production environment...

I tried to remove header in Method Response and add again, through the same web UI.

This is exported Swagger - for the same part as in screenshot. Here you can see my method.response.header.Access-Control-Allow-Origin. So in browser UI and exported file are not the same!

paths:
  /lineupmaps:
    get:
      consumes:
      - "application/json"
      produces:
      - "application/json"
      responses:
        200:
          description: "200 response"
          schema:
            $ref: "#/definitions/Empty"
          headers:
            Access-Control-Allow-Origin:
              type: "string"
      security:
      - cognito: []
      x-amazon-apigateway-integration:
        uri: "arn:aws:apigateway:us-east-1:lambda:path/2015-03-31/functions/arn:aws:lambda:us-east-1:988646599334:function:getLineUpMap/invocations"
        responses:
          default:
            statusCode: "200"
            responseParameters:
              method.response.header.access-control-allow-origin: "'https://happy-marketer.gms-ai.com'"
            responseTemplates:
              application/json: "$input.body"
        passthroughBehavior: "when_no_match"
        httpMethod: "POST"
        requestTemplates:
          application/json: "{\n    \"specs\": $input.params('specs'),\n    \"competitors\"\
            : $input.params('competitors'),\n    \"numberOfModels\": $input.params('numberOfModels')\n\
            }"
        contentHandling: "CONVERT_TO_TEXT"
        type: "aws"
    options:
      consumes:
      - "application/json"
      produces:
      - "application/json"
      responses:
        200:
          description: "200 response"
          schema:
            $ref: "#/definitions/Empty"
          headers:
            Access-Control-Allow-Origin:
              type: "string"
            Access-Control-Max-Age:
              type: "string"
            Access-Control-Allow-Headers:
              type: "string"
      x-amazon-apigateway-integration:
        responses:
          default:
            statusCode: "200"
            responseParameters:
              method.response.header.Access-Control-Max-Age: "'86400'"
              method.response.header.Access-Control-Allow-Headers: "'Authorization'"
              method.response.header.Access-Control-Allow-Origin: "'https://happy-marketer.gms-ai.com'"
        passthroughBehavior: "when_no_match"
        requestTemplates:
          application/json: "{\"statusCode\": 200}"
        type: "mock"

Tried to import exported Swagger, also with commented/removed responseParameters block: still the same error:

Answer 1

Thank you nachary: helped importing of my Swagger with removed method.response.header.access-control-allow-origin in the GET of one endpoint...