VisualElementRenderer UpdateTabStop Error

[n/a]

Hi,

I am getting an error with the SideDrawer after updating to the latest version of Xamarin Forms, the issue seems to occur when the back button is clicked and the SideDrawer is visible, we also have a TabbedPage in our app and if you click the same tab as is visible when the SideDrawer is visible it causes the same crash.

We use Azure mobile app centre, so all the information for the crash is below:

Xamarin.Forms Version - 3.3.0.912540

Telerik.UI Version - 2018.3.1018.1, we had the same issue with previous build too 2018.2.620.2 but tried upgrading.

 

Error is:

VisualElementRenderer`1[TElement].UpdateTabStop ()
System.NullReferenceException: Object reference not set to an instance of an object

Threads:

VisualElementRenderer`1[TElement].UpdateTabStop ()
IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element)
RadPlatform.RetireRenderer (Xamarin.Forms.VisualElement visualElement)
RadViewContainer.ClearContainer ()
RadViewContainer.Dispose (System.Boolean disposing)
NSObject.Dispose ()
SideDrawerRenderer.OnElementDetached (Telerik.XamarinForms.Primitives.RadSideDrawer oldElement)
IosRendererBase`2[S,T].OnElementChanged (Xamarin.Forms.Platform.iOS.ElementChangedEventArgs`1[TElement] e)
VisualElementRenderer`1[TElement].SetElement (TElement element)
VisualElementRenderer`1[TElement].Dispose (System.Boolean disposing)
ViewRenderer`2[TView,TNativeView].Dispose (System.Boolean disposing)
NSObject.Dispose ()
DisposeHelpers.DisposeModalAndChildRenderers (Xamarin.Forms.Element view)
Platform.HandleChildRemoved (System.Object sender, Xamarin.Forms.ElementEventArgs e)
Element.OnDescendantRemoved (Xamarin.Forms.Element child)
Element.OnDescendantRemoved (Xamarin.Forms.Element child)
Element.OnChildRemoved (Xamarin.Forms.Element child)
VisualElement.OnChildRemoved (Xamarin.Forms.Element child)
Page.OnInternalRemoved (Xamarin.Forms.VisualElement view)
Page.InternalChildrenOnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedAction action, System.Object item, System.Int32 index)
ObservableCollection`1[T].RemoveItem (System.Int32 index)
Collection`1[T].Remove (T item)
NavigationPage+<Xamarin-Forms-INavigationPageController-RemoveAsyncInner>d__69.MoveNext ()
TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task)
TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task)
TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task)
TaskAwaiter`1[TResult].GetResult ()
NavigationRenderer+<UpdateFormsInnerNavigation>d__75.MoveNext ()
TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task)
TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task)
TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task)
TaskAwaiter.GetResult ()
NavigationRenderer+ParentingViewController+<DidMoveToParentViewController>d__41.MoveNext ()
AsyncMethodBuilderCore+<>c.<ThrowAsync>b__6_0 (System.Object state)
NSAsyncSynchronizationContextDispatcher.Apply ()
(wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate)
UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName)
Application.Main (System.String[] args)

[Lance | Manager Technical Support]

Hello Adam,

This is happening because of a bug in Xamarin.Forms 3.3. We have identified the issue, reported it to Microsoft and they've already worked on a fix.

You can find the Issue thread here: https://github.com/xamarin/Xamarin.Forms/issues/4146

In the meantime, I don't have any solution other than to downgrade to Xamarin.Forms 3.2.

Regards,
Lance | Tech Support Engineer, Sr.
Progress Telerik

[n/a]

Hi Lance,

Thanks for your quick response, I have rolled back to 3.2 and will await their fix!

Regards

Adam