Call blocked: Origin 'null' is therefore not allowed access

[pwFoo]

Found #26 with the set header example

var request = ajax({
  headers: { 'content-type': null }
})

request.post(url, FormObj)
  .then(function (data) {
    // success
    console.log(data)
  })
  .catch(function (err) {
    // error
    console.log(err)
  })

Tried to add the header and send the call with one single ajax() method call.

      $.ajax({
            method: 'get',
            url: 'https://www.google.de'
        })

        $.ajax({
            method: 'get',
            headers: {
                'Access-Control-Allow-Origin': '*'
            },
            url: 'https://www.google.de'
        })

And geht errors:

without header

XMLHttpRequest cannot load https://www.google.de/. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.

and with header

XMLHttpRequest cannot load https://www.google.de/. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 405.

So maybe I tried it the wrong way? Could you help me with a hint about the problem?

[pwFoo]

Got it... server side problem ;)
No problem from the same origin...