AMP Access-Control-Allow-Credentials Error

I have problem After google cache my AMP page. I am implementing amp page with rails 5. Using rake-cors gem for cross-origin. Normally page working fine but after the cache is shown console error.

Error:

The value of the 'Access-Control-Allow-Credentials' header in the response is '' which must be 'true' when the request's credentials mode is 'include'. Origin 'https://www-myurl-in.cdn.ampproject.org' is therefore not allowed access.

config/application.rb

    config.middleware.insert_before 0, Rack::Cors do
      allow do
        origins 'https://www-myurl-in.cdn.ampproject.org'
        resource '*', :headers => :any, :methods => [:get, :post, :options]
      end
    end

I don't know where I change in my code, Please help me.

After modifying Response Header its working fine.

response.headers['AMP-Redirect-To'] = request.protocol+request.host_with_port+url
response.headers['Access-Control-Expose-Headers'] = 'AMP-Redirect-To, AMP-Access-Control-Allow-Source-Origin'
response.headers['AMP-Access-Control-Allow-Source-Origin'] = params[:__amp_source_origin]