Xamarin Forms Android System Exception "Android only allows one navigation page on screen at a time"

Question

Recently i decided to give Xamarin Forms a try, so i started migrating my Windows Phone / Android Xamarin project, to the new "Forms" format.

After migrating two simple screens (views), the code runs just fine on my Windows Phone, but it crashes on the Android Platform. I am using two devices to test the code, with no emulator to avoid unecessary headaches.

The exception raised on the android platform is: System.Exception: Android only allows one navigation page on screen at a time.

The problem is not related to the "View" class itself, since it doesn`t happen once i set it as the "start screen" for the Android.

I'm afraid the problem is related to the fact that i am "Pushing" two screens via the "Navigation.PushAsync(...)" method provided by Xamarin.

Any ideas on how do actually fix it ?

EDIT:

Code Sample

Overview: The "MainView.cs" is just a content page with a label on the top, followed by two buttons alligned vertically.

How to reproduce the exception: Click on "Get All Users" button on the mainview. I have modified the code to push the same view once the button is clicked, instead of pushing another view (The view that has a listview of users, which i haven't included, just to make it simple). Once the button is clicked, it will navigate to a new instance of "MainView" by calling "Navigation.PushAsync(...)". This will trigger the exception after the screen is loaded.

Added a code sample with some minor overview of the exception and how to reproduce it. Let me know if you need anything else. — Marcello Grechi Lins
– Marcello Grechi Lins, Commented Jun 14, 2014 at 17:06
Please post code inline, properly formatted, instead of using an external link. — Jason
– Jason, Commented Jun 14, 2014 at 17:25

Jason · Accepted Answer · 2014-06-14 17:28:18Z

3

You are nesting Navigation pages. This is not necessary. Try this instead:

public class ViewsHandler
{
        public static Page GetMainPage()
        {
            return new MainView();
        }

        public static Page GetUsersListPage()
        {
            return new UsersListView ();
        }
}

public class MainActivity : AndroidActivity
{
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Initializing Xamarin Form
            Xamarin.Forms.Forms.Init (this, bundle);

            // create a single NavigationPage wrapping your content
            SetPage (new NavigationPage(ViewsHandler.GetMainPage()));
        }
}

answered Jun 14, 2014 at 17:28

Jason

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2 Comments

Marcello Grechi Lins Over a year ago

Solved my problem. Would you mind explaining a little bit more, WHY does it work?

Jason Over a year ago

In your original code, you were pushing a NavigationPage onto an already existing navigation stack. You only need one NavigationPage in a hierarchy.

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