java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState on Xamarin.Forms

Question

I have this snippet of code and intermittently, my deploy fails because of an IllegalStateException:

It fails here in app.cs:

void appInitializer_OnDisplayOffers(object sender, System.EventArgs e)
{
    Device.BeginInvokeOnMainThread(() => {
        Xamarin.Forms.Application.Current.MainPage = App.MainLandingPage(false);
    });
}

Where:

public static Page MainLandingPage(bool isReceiptSubmitSuccess = false)
        {
            if (Navigation != null && Navigation.ModalStack.Count == 1)
                Navigation.PopModalAsync();
            return new RootPage();
        }

Here's some info on where it's triggered:

protected override void OnAppearing()
{
    base.OnAppearing();

    timer.Enabled = true;
    timer.AutoReset = false;
    timer.Elapsed += timer_Elapsed;
}

void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
    timer.Enabled = false;
    appInitializer.OnDisplayOffers += appInitializer_OnDisplayOffers;

    appInitializer.ValidateLogin();
}

where:

  // Timer has been added to delay loading of the next screen
  System.Timers.Timer timer = new System.Timers.Timer(2000);

Here's the exception details:

04-20 12:42:26.304 I/MonoDroid( 2886): UNHANDLED EXCEPTION:
04-20 12:42:26.304 I/MonoDroid( 2886): Java.Lang.IllegalStateException: Can not perform this action after onSaveInstanceState
04-20 12:42:26.304 I/MonoDroid( 2886):   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/3053/a94a03b5/source/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Android.Runtime.JNIEnv.CallIntMethod (IntPtr jobject, IntPtr jmethod) [0x00063] in /Users/builder/data/lanes/3053/a94a03b5/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:386 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Android.Support.V4.App.FragmentTransactionInvoker.Commit () [0x00033] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer.SwitchContentAsync (Xamarin.Forms.Page view, Boolean animated, Boolean removed, Boolean popToRoot) [0x0013f] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer.OnPushAsync (Xamarin.Forms.Page view, Boolean animated) [0x00000] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer.PushViewAsync (Xamarin.Forms.Page page, Boolean animated) [0x00000] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer.<OnElementChanged>b__13_0 (Xamarin.Forms.Page p) [0x00000] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.EnumerableExtensions.ForEach[T] (IEnumerable`1 enumeration, System.Action`1 action) [0x00010] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer.OnElementChanged (Xamarin.Forms.Platform.Android.ElementChangedEventArgs`1 e) [0x001af] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].SetElement (Xamarin.Forms.Platform.Android.TElement element) [0x000fc] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].Xamarin.Forms.Platform.Android.IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x00027] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.Platform.CreateRenderer (Xamarin.Forms.VisualElement element) [0x0001f] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.MasterDetailContainer.set_ChildView (Xamarin.Forms.VisualElement value) [0x0003d] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.MasterDetailPageRenderer.UpdateDetail () [0x0001d] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.MasterDetailPageRenderer.Xamarin.Forms.Platform.Android.IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x0012c] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.Platform.CreateRenderer (Xamarin.Forms.VisualElement element) [0x0001f] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.RendererFactory.GetRenderer (Xamarin.Forms.VisualElement view) [0x00000] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.Platform.AddChild (Xamarin.Forms.Page page, Boolean layout) [0x00015] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.AppCompat.Platform.SetPage (Xamarin.Forms.Page newRoot) [0x00090] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.InternalSetPage (Xamarin.Forms.Page page) [0x0001a] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.AppOnPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs args) [0x0001e] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00012] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Xamarin.Forms.Application.set_MainPage (Xamarin.Forms.Page value) [0x0008b] in <filename unknown>:0 
04-20 12:42:26.304 I/MonoDroid( 2886):   at ProjectName.Core.UI.XamarinForms.LaunchPage+<>c.<appInitializer_OnDisplayOffers>b__6_0 () [0x00001] in C:\Users\~\Documents\ProjectNameMobile4\ProjectName\main\Mobile\ProjectName.Core\UI\XamarinForms\App.cs:312 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Java.Lang.Thread+RunnableImplementor.Run () [0x0000b] in /Users/builder/data/lanes/3053/a94a03b5/source/monodroid/src/Mono.Android/src/Java.Lang/Thread.cs:36 
04-20 12:42:26.304 I/MonoDroid( 2886):   at Java.Lang.IRunnableInvoker.n_Run (IntPtr jnienv, IntPtr native__this) [0x00009] in /Users/builder/data/lanes/3053/a94a03b5/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Java.Lang.IRunnable.cs:71 
04-20 12:42:26.304 I/MonoDroid( 2886):   at (wrapper dynamic-method) System.Object:b6e56cfb-0162-4eab-9d72-3563aee71861 (intptr,intptr)
 --- End of managed exception stack trace --- 
java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1448)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1466)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:634)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:613)
04-20 12:42:26.304 I/MonoDroid( 2886):  at mono.java.lang.RunnableImplementor.n_run(Native Method)
04-20 12:42:26.304 I/MonoDroid( 2886):  at mono.java.lang.RunnableImplementor.run(RunnableImplementor.java:29)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.os.Handler.handleCallback(Handler.java:733)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.os.Handler.dispatchMessage(Handler.java:95)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.os.Looper.loop(Looper.java:136)
04-20 12:42:26.304 I/MonoDroid( 2886):  at android.app.ActivityThread.main(ActivityThread.java:5017)
04-20 12:42:26.304 I/MonoDroid( 2886):  at java.lang.reflect.Method.invokeNative(Native Method)
04-20 12:42:26.304 I/MonoDroid( 2886):  at java.lang.reflect.Method.invoke(Method.java:515)
04-20 12:42:26.304 I/MonoDroid( 2886):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-20 12:42:26.304 I/MonoDroid( 2886):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-20 12:42:26.304 I/MonoDroid( 2886):  at dalvik.system.NativeStart.main(Native Method)

My project does not use any fragments or a fragment manager of any kind. This happens in Xamarin.Forms for Android.

I should mention restarting Visual Studio, the emulator or rebuilding usually "fixes" it for a little bit until the issue happens again at random. My team is stumped by this and they just deal with it. I am curious why it's happening and if there's a solution.

Is `appInitializer_OnDisplayOffers` an event handler? If so, what does it get hooked up to? The error you're seeing occurs because the app is backgrounded and Xamarin Forms is trying to reuse the main page fragment (Xamarin.Forms for Android uses fragments to represent pages). — matthewrdev, Apr 21 '16 at 07:16
Please include the context that the `appInitializer_OnDisplayOffers` is triggered. — matthewrdev, Apr 21 '16 at 07:16
@matthewrdev, updated my post. Thank you so much for your help! — Kala J, Apr 21 '16 at 12:01
Possible duplicate of [App resuming results in crash with FormsAppCompatActivity](http://stackoverflow.com/questions/35892598/app-resuming-results-in-crash-with-formsappcompatactivity) — Korayem, Feb 19 '17 at 07:13

score 0 · Answer 1 · answered Apr 27 '16 at 17:53

0

I'm not sure what the real solution for this would be but there's 2 things I would suggest looking at.

First in pretty much every timer example I've seen used it's always the Device timer like this.

Device.StartTimer(TimeSpan.FromSeconds(4), SaveChangesTick);

This also seems to fit the description of what you are seeing. Link

answered Apr 27 '16 at 17:53

Jazzeroki

173
1
3
15

What is SaveChangesTick in this example? – Kala J Apr 27 '16 at 18:13

java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState on Xamarin.Forms

1 Answers1