Push notification Class not found error

I tried to implement the native Push notification, but when i build android app, i get
Class not found error.

25    764231   error    EXCEPTION: Uncaught (in promise): Class not found
26    764231   error    ORIGINAL STACKTRACE:
27    764232   error    Error: Uncaught (in promise): Class not found
    at s (http://192.168.0.20:8100/build/polyfills.js:3:8568)
    at s (http://192.168.0.20:8100/build/polyfills.js:3:8391)
    at http://192.168.0.20:8100/build/polyfills.js:3:8902
    at t.invokeTask (http://192.168.0.20:8100/build/polyfills.js:3:14051)
    at Object.onInvokeTask (webpack:///./~/@angular/core/src/zone/ng_zone.js?:229:37)
    at t.invokeTask (http://192.168.0.20:8100/build/polyfills.js:3:13987)
    at e.runTask (http://192.168.0.20:8100/build/polyfills.js:3:11411)
    at i (http://192.168.0.20:8100/build/polyfills.js:3:8028)
28    764234   error    Unhandled Promise rejection:, Class not found, ; Zone:, angular, ; Task:, Promise.then, ; Value:, Class not found,

I followed Ionic Push Notification - Android and iOS working to get Push notification.

I have installed according to http://ionicframework.com/docs/v2/native/push/
but not working.

here is the snippet of my code

  import { Push } from 'ionic-native';

  this.platform.ready().then(() => {
  console.log('11111111');
  let push = Push.init({
    android: {
      senderID: "xxxxxxx"
    },
    ios: {
      alert: "true",
      badge: false,
      sound: "true"
    },
    windows: {}
  });

  push.on('registration', (data) => {
    console.log("device token ->", data.registrationId);
    console.log(data.registrationId);
  });


  push.on('notification', (data) => {
    console.log('message', data.message);
    let self = this;
    if (data.additionalData.foreground) {
      let confirmAlert = this.alertCtrl.create({
        title: 'New Notification',
        message: data.message,
        buttons: [{
          text: 'Ignore',
          role: 'cancel'
        }, {
          text: 'View',
          handler: () => {
            self.nav.push(DetailView, {data: data});
          }
        }]
      });
      confirmAlert.present();
    } else {
      self.nav.push(DetailView, {data: data});
      console.log("Push notification clicked");
    }
  });
  push.on('error', (e) => {
    console.log(e.message);
  });

});

this is my system information:

Cordova CLI: 6.3.1 
Ionic Framework Version: 2.0.0-rc.2
Ionic CLI Version: 2.1.8
Ionic App Lib Version: 2.1.4
Ionic App Scripts Version: 0.0.43
ios-deploy version: 1.8.6 
ios-sim version: 5.0.9 
OS: macOS Sierra
Node Version: v6.9.1
Xcode version: Xcode 8.1 Build version 8B62

Did you find a fix for this? I am also getting a similar error that I’m not sure where it is coming from (might be push notifications)

I found out that I didn’t install ionic and cordova properly.

uninstall ionic and cordova
reinstall ionic and cordova

this worked for me.