title: Xamarin Forms user login and logout not working on Android
body: <p>I have problem with login and logout user. If in first time i click button login and after click logout everything works good but if i again launch app i have only blank page and i have to uninstall app thaht works like in first case</p>
  
  <p>App.cs Code:</p>
  
  <pre><code>public App()
  {
      InitializeComponent();
  
       if (!Current.Properties.ContainsKey("IsLoggedIn"))
       {
          Current.Properties["IsLoggedIn"] = false;
          if ((bool)Current.Properties["IsLoggedIn"] == false)
          {
              MainPage = new LoginPage();
          }
          else
          {
              MainPage = new NavigationPage(new MainPage());
          }
       }
  }
  </code></pre>
  
  <p>Login Page:</p>
  
  <pre><code>async private void Button_Clicked_Login(object sender, EventArgs e)
  {
     Application.Current.Properties["IsLoggedIn"] = true;
     await Application.Current.SavePropertiesAsync();
     Application.Current.MainPage = new NavigationPage(new MainPage());
  }
  </code></pre>
  
  <p>Logout:</p>
  
  <pre><code> async private void Button_Clicked(object sender, EventArgs e)
   {
      Application.Current.Properties["IsLoggedIn"] = false;
      await Application.Current.SavePropertiesAsync();
      Application.Current.MainPage = new LoginPage();
   }
  </code></pre>