How to connect my server with my ember cli App

my server is working on the port :3000 and i am using node, express on server side and this is working fine while using curl or REST client.

ember cli server is working on port :4200

I added this code on environment.js for connecting server to client.

contentSecurityPolicy: {
              'default-src': "'none'",
              'script-src': "'self' 'unsafe-inline' 'unsafe-eval'",
              'font-src': "'self'",
              'connect-src': "'self' http://localhost:3000",
              'img-src': "'self'",
              'report-uri':"'localhost'",
              'style-src': "'self' 'unsafe-inline'",
              'frame-src': "'none'"
     }

and my application adapter code is:

import JSONAPIAdapter from 'ember-data/adapters/json-api';

export default JSONAPIAdapter.extend({
    "host": "http://localhost:3000",
    "namespace": "api"
});

running my ember server on this way ember server --proxy http://127.0.0.1:3000 on controller i use ajax call :

            $.ajax({
                    type: 'POST',
                    url: '/blog',
                    contentType: 'application/json',
                    data: param,
                    processData: false,
                    success :
              });

it getting an error: POST http://localhost:4200/blog 500 (Internal Server Error)

i have done all these but i don't know why it's not working. please help me if you have any idea for that .