NullReferenceException when reloading ObservableCollection<T>

[Joseph Canada]

Good Day,

We have experienced something weird on the DataGrid when we try to reload the data inside the item source thru ObservableCollection. The app throws this exception which is something we don't understand why. The issue we encountered was with v14.4.0.15 and v14.4.0.20; On the previous version, we didn't experienced this kind of error.

Please help us ASAP!

Thank you.

See below this is the exception that was thrown by the application;

01-30 14:07:11.243 I/MonoDroid(14942): System.NullReferenceException: Object reference not set to an instance of an object.

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.Platform.Android.VisualElementPackager.RemoveChild (Xamarin.Forms.VisualElement view) [0x00014] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\VisualElementPackager.cs:139 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.Platform.Android.VisualElementPackager.OnChildRemoved (System.Object sender, Xamarin.Forms.ElementEventArgs e) [0x0000f] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\VisualElementPackager.cs:125 

01-30 14:07:11.243 I/MonoDroid(14942):   at (wrapper delegate-invoke) System.EventHandler`1[Xamarin.Forms.ElementEventArgs]:invoke_void_object_TEventArgs (object,Xamarin.Forms.ElementEventArgs)

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.Element.OnChildRemoved (Xamarin.Forms.Element child) [0x0000f] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:356 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.VisualElement.OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\VisualElement.cs:577 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.Layout`1[T].OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\Layout.cs:39 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.Layout.OnInternalRemoved (Xamarin.Forms.View view) [0x00012] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\Layout.cs:412 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.Layout.InternalChildrenOnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x0002f] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\Layout.cs:376 

01-30 14:07:11.243 I/MonoDroid(14942):   at (wrapper delegate-invoke) <Module>:invoke_void_object_NotifyCollectionChangedEventArgs (object,System.Collections.Specialized.NotifyCollectionChangedEventArgs)

01-30 14:07:11.243 I/MonoDroid(14942):   at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00012] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/System/compmod/system/collections/objectmodel/observablecollection.cs:288 

01-30 14:07:11.243 I/MonoDroid(14942):   at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedAction action, System.Object item, System.Int32 index) [0x00000] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/System/compmod/system/collections/objectmodel/observablecollection.cs:351 

01-30 14:07:11.243 I/MonoDroid(14942):   at System.Collections.ObjectModel.ObservableCollection`1[T].RemoveItem (System.Int32 index) [0x0002b] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/System/compmod/system/collections/objectmodel/observablecollection.cs:205 

01-30 14:07:11.243 I/MonoDroid(14942):   at System.Collections.ObjectModel.Collection`1[T].Remove (T item) [0x0002d] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/mscorlib/system/collections/objectmodel/collection.cs:113 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.ObservableWrapper`2[TTrack,TRestrict].Clear () [0x00030] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\ObservableWrapper.cs:45 

01-30 14:07:11.243 I/MonoDroid(14942):   at Syncfusion.SfDataGrid.XForms.VisualContainer.OnItemsSourceChanged () [0x00014] in <0e18c3999f324e928a6ea83b75eca1f0>:0 

01-30 14:07:11.243 I/MonoDroid(14942):   at Syncfusion.SfDataGrid.XForms.SfDataGrid.OnItemsSourceChanged (Xamarin.Forms.BindableObject bindable, System.Object oldValue, System.Object newValue) [0x000ce] in <0e18c3999f324e928a6ea83b75eca1f0>:0 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.BindableObject+SetValueFlags attributes, System.Boolean silent) [0x00108] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:584 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.BindableObject+SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0014b] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:378 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, System.Boolean fromTarget) [0x0020c] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\BindingExpression.cs:177 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.BindingExpression.Apply (System.Boolean fromTarget) [0x0003e] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\BindingExpression.cs:55 

01-30 14:07:11.243 I/MonoDroid(14942):   at Xamarin.Forms.BindingExpression+BindingExpressionPart.<PropertyChanged>b__44_0 () [0x00000] in C:\BuildAgent2\work\aad494dc9bc9783\Xamarin.Forms.Core\BindingExpression.cs:475 

01-30 14:07:11.243 I/MonoDroid(14942):   at Java.Lang.Thread+RunnableImplementor.Run () [0x0000b] in /Users/builder/data/lanes/3511/501e63ce/source/xamarin-android/src/Mono.Android/Java.Lang/Thread.cs:36 

01-30 14:07:11.243 I/MonoDroid(14942):   at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00009] in /Users/builder/data/lanes/3511/501e63ce/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Java.Lang.IRunnable.cs:81 

01-30 14:07:11.243 I/MonoDroid(14942):   at (wrapper dynamic-method) System.Object:c285725e-01d0-4700-bd9d-1c0fd756cb81 (intptr,intptr)

https://www.syncfusion.com/support/directtrac/incidents/171727

[Ashok N]

Hi Joseph, 

 

Thanks for contacting Syncfusion support. 

 

We are able to reproduce the reported NullReferenceException and we are updated the details in your below mentioned incident, Please refer that incident for further updates.  

 

Regards, 

Ashok