Get http status : 0 when using GET method?

Ionic Framework ionic-v3
1

I got this error.

{"_body":{"isTrusted":true},"status":0,"ok":false,"statusText":"","headers":{},"type":3,"url":null}

When try to get data from local server.

I ever got problem like this when use POST method with Content-type: application/json. It about CORS and I already solve this problem.

But why It happen with GET method. Or I made some thing wrong, I try with Postman it was fine.

This is my code

  get(uri) : Promise<any> {

    let options = new RequestOptions({
      headers: new Headers({
        'Authorization' : 'Bearer ' + this.user.data.access_tokens
      })
    });
    let end_point = this.api_server + uri;
    console.log('GET : ' + end_point);
    // console.log(JSON.stringify(options));

    return this.http.get(end_point,  options)
    .toPromise()
    .then(response => Promise.resolve(response.json()) )
    .catch(error =>  Promise.reject(error) );

  }

But POST method didn’t get any error.

  post(uri, data) : Promise<any> {

    let options = new RequestOptions({
      headers: new Headers({
        'Content-Type': 'application/json',
        'Authorization' : 'Bearer ' + this.user.data.access_tokens
      })
    });
    let end_point = this.api_server + uri;
    console.log('POST : ' + end_point, JSON.stringify(data));
    // console.log(JSON.stringify(options));

    return this.http.post(end_point, data, options)
    .toPromise()
    .then(response => Promise.resolve(response.json()) )
    .catch(error =>  Promise.reject(error) );
  }

ionic info

cli packages: (/usr/local/lib/node_modules)

@ionic/cli-utils  : 1.18.0
ionic (Ionic CLI) : 3.18.0

global packages:

cordova (Cordova CLI) : 6.5.0

local packages:

@ionic/app-scripts : 3.1.0
Cordova Platforms  : ios 4.5.3
Ionic Framework    : ionic-angular 3.9.2

System:

ios-deploy : 1.9.2 
ios-sim    : 6.1.2 
Node       : v6.11.0
npm        : 5.5.1 
OS         : macOS High Sierra
Xcode      : Xcode 9.1 Build version 9B55

Environment Variables:

ANDROID_HOME : not set

Misc:

backend : legacy

Ps. http is @angular/http