iOS App crashes after update

[doudouLin]

I just updated my MAC system and all packages in my Xamarin Project, now the App always crashes due to the following exception:
Object reference not set to an instance of an object
at XamForms.Controls.iOS.CalendarButtonRenderer.OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x0004a] in :0
at (wrapper delegate-invoke) .invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs)
at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:229
at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:350
at Xamarin.Forms.BindableObject.ClearValue (Xamarin.Forms.BindableProperty property, System.Boolean fromStyle, System.Boolean checkAccess) [0x000c6] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:96
at Xamarin.Forms.BindableObject.ClearValue (Xamarin.Forms.BindableProperty property) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:48
at Xamarin.Forms.Platform.iOS.VisualElementRenderer1[TElement].Dispose (System.Boolean disposing) [0x0007d] in <db18f72e3204406988680543da513ace>:0 at Xamarin.Forms.Platform.iOS.ViewRenderer2[TView,TNativeView].Dispose (System.Boolean disposing) [0x0005c] in :0
at Xamarin.Forms.Platform.iOS.ButtonRenderer.Dispose (System.Boolean disposing) [0x00064] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\ButtonRenderer.cs:66
at Foundation.NSObject.Dispose () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/13.4.0.2/src/Xamarin.iOS/Foundation/NSObject2.cs:147
at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose (System.Boolean disposing) [0x0003f] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:71
at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose () [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:39
at Xamarin.Forms.Platform.iOS.VisualElementRenderer1[TElement].Dispose (System.Boolean disposing) [0x00058] in <db18f72e3204406988680543da513ace>:0 at Foundation.NSObject.Dispose () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/13.4.0.2/src/Xamarin.iOS/Foundation/NSObject2.cs:147 at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose (System.Boolean disposing) [0x0003f] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:71 at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose () [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:39 at Xamarin.Forms.Platform.iOS.VisualElementRenderer1[TElement].Dispose (System.Boolean disposing) [0x00058] in :0
at Foundation.NSObject.Dispose () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/13.4.0.2/src/Xamarin.iOS/Foundation/NSObject2.cs:147
at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildRemoved (Xamarin.Forms.VisualElement view) [0x0003e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:124
at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildRemoved (System.Object sender, Xamarin.Forms.ElementEventArgs e) [0x0000f] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:161
at Xamarin.Forms.Element.OnChildRemoved (Xamarin.Forms.Element child) [0x00007] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:334
at Xamarin.Forms.VisualElement.OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\VisualElement.cs:750
at Xamarin.Forms.TemplatedView.OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\TemplatedView.cs:92
at Xamarin.Forms.Layout.OnInternalRemoved (Xamarin.Forms.View view) [0x00012] in D:\a\1\s\Xamarin.Forms.Core\Layout.cs:473
at Xamarin.Forms.Layout.InternalChildrenOnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x0002b] in D:\a\1\s\Xamarin.Forms.Core\Layout.cs:436
at System.Collections.ObjectModel.ObservableCollection1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00018] in <429bba1022b24f41b20fdc67c7554c2d>:0 at System.Collections.ObjectModel.ObservableCollection1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedAction action, System.Object item, System.Int32 index) [0x00009] in <429bba1022b24f41b20fdc67c7554c2d>:0
at System.Collections.ObjectModel.ObservableCollection1[T].RemoveItem (System.Int32 index) [0x00021] in <429bba1022b24f41b20fdc67c7554c2d>:0 at System.Collections.ObjectModel.Collection1[T].RemoveAt (System.Int32 index) [0x00027] in :0
at Xamarin.Forms.TemplateUtilities.OnContentChanged (Xamarin.Forms.BindableObject bindable, System.Object oldValue, System.Object newValue) [0x00018] in D:\a\1\s\Xamarin.Forms.Core\TemplateUtilities.cs:63
at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00120] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:463
at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x00173] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:397
at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x00042] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:334
at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:311
at Xamarin.Forms.ContentView.set_Content (Xamarin.Forms.View value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\ContentView.cs:11
at XamForms.Controls.Calendar+<>c__DisplayClass89_0.b__0 () [0x00027] in <78f786ab622940c1b06f4cfd4c30dce1>:0
at Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/13.4.0.2/src/Xamarin.iOS/Foundation/NSAction.cs:152
at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
at UIKit.UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) [0x00005] in /Library/Frameworks/Xamarin.iOS.framework/Versions/13.4.0.2/src/Xamarin.iOS/UIKit/UIApplication.cs:86
at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0000e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/13.4.0.2/src/Xamarin.iOS/UIKit/UIApplication.cs:65
at myproject.iOS.Application.Main (System.String[] args) [0x00001] in /Users/lin/Projects/myProject/iOS/Main.cs:12

[lubiepomaranczki]

Hey @doudouLin,
as you may have seen Rebecca is no longer supporting this repository. The last commit was pushed 2years ago. Please, try this package instead

If something is not working, please open an issue

[doudouLin]

@lubiepomaranczki hi, thank you for the information. I actually tried to install this package in PCL project, but can't manage it. Got error that not supported by my PCL project. My PCL project is profile111

[lubiepomaranczki]

That's true that it ain't support profile111. The problem is: this package doesn't support new version of Xamarin.Forms and the one I wrote about doesn't support profile111. One more change is that it does not support UWP.

I'd like to advise that you migrate to .NET standard. It's not that hard, .NET standard has backwards compatibility and you will be able to use more packages.

[doudouLin]

I am just concerned that if I migrate to. Net standard, I get problem with some other packages in the project. But I will try it tomorrow morning. Is that possible to write you email? Thank you for your help!

[lubiepomaranczki]

You can use both .NET standard and pcl packages in your project. You may find these blog post helpful:

• migrating to .NET standard
• using PCL packages in .NET standard

If you still want, you leave me an email at develop(at)lukaszlawicki.pl

[doudouLin]

Thank you very much!!!