fix

config.xml

@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding='utf-8'?>
-<widget id="com.coregrade.users" version="10.0.13" xmlns="http://www.w3.org/ns/widgets" xmlns:cdv="http://cordova.apache.org/ns/1.0">
+<widget id="com.coregrade.users" version="10.0.14" xmlns="http://www.w3.org/ns/widgets" xmlns:cdv="http://cordova.apache.org/ns/1.0">
     <name>CoreGrade</name>
     <description>Intelligent Learning Platform.</description>
     <author email="support@coregrade.com" href="https://www.coregrade.com/">CoreGrade</author>

src/app/login/login.page.ts

@@ -1,6 +1,8 @@
 import { Router } from '@angular/router';
-import { Component, OnInit } from '@angular/core';
+import { Component, OnInit, ViewChild } from '@angular/core';
+import { AlertController } from '@ionic/angular';
 
+AlertController
 
 @Component({
   selector: 'app-login',
@@ -9,13 +11,37 @@ import { Component, OnInit } from '@angular/core';
 })
 export class LoginPage implements OnInit {
 
-  constructor( private router:Router) { }
+  @ViewChild('username', { static: false }) username;
+  @ViewChild('password', { static: false }) password;
+
+
+  constructor(
+    private alertCtrl: AlertController,
+    private router: Router
+    ) { }
 
   ngOnInit() {
   }
 
-  onStartLogin(){
+  async  onStartLogin() {
-    this.router.navigateByUrl('tabs');
+    if (this.username == null || this.username === '' /* || this.floatValidatorsProvider.validateEmail(this.username) === false */
+      || this.password == null || this.password === '') {
+      this.showAlert('Invalid Login', 'Enter username(email) and password to login');
+    } else {
+
+      this.router.navigateByUrl('tabs');
+    }
+
 
   }
+
+  async showAlert(mtitle: string, amessage: string) {
+    const alert = await this.alertCtrl.create({
+      header: mtitle,
+      message: amessage,
+      buttons: ['OK']
+    });
+    alert.present();
+  }
+
 }