Object reference not set to an instance of an object

[Marco Abergo]

I have a CarouselPage with three ContentPage.

In each ContentPage I have a RadPieChart. I have a refresh button on the toolbar that read the data and refresh all the pie charts.

If I press the refresh button on the first or on the second ContentPage all is ok.

If I press the refresh button on the third page I have this error:

Object reference not set to an instance of an object

Can you help me???

The call stack is:

  at Telerik.XamarinForms.ChartRenderer.Android.PieChartRenderer.SeriesInternal_CollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00028] in <filename unknown>:0 
  at (wrapper delegate-invoke) <Module>:invoke_void_object_NotifyCollectionChangedEventArgs (object,System.Collections.Specialized.NotifyCollectionChangedEventArgs)
  at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00012] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/System/compmod/system/collections/objectmodel/observablecollection.cs:288 
  at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (NotifyCollectionChangedAction action, System.Object item, Int32 index) [0x00000] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/System/compmod/system/collections/objectmodel/observablecollection.cs:351 
  at System.Collections.ObjectModel.ObservableCollection`1[T].InsertItem (Int32 index, System.Collections.ObjectModel.T item) [0x00024] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/System/compmod/system/collections/objectmodel/observablecollection.cs:219 
  at Telerik.XamarinForms.Chart.ElementsCollection`1[T].InsertItem (Int32 index, Telerik.XamarinForms.Chart.T item) [0x0001b] in <filename unknown>:0 
  at System.Collections.ObjectModel.Collection`1[T].Add (System.Collections.ObjectModel.T item) [0x00023] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/collections/objectmodel/collection.cs:67 
  at MobileCRM.Shared.DashboardView+<>c__DisplayClass2_0.<.ctor>b__1 (System.Collections.Generic.List`1 datiAttivita) [0x00360] in D:\Prj3rd\OndaCRMApp\Client\MobileCRM.Shared\Pages\Home\DashboardView.xaml.cs:212 
  at Xamarin.Forms.MessagingCenter+<>c__DisplayClass4_0`1[TSender].<Subscribe>b__0 (System.Object sender, System.Object args) [0x00027] in C:\BuildAgent3\work\aad494dc9bc9783\Xamarin.Forms.Core\MessagingCenter.cs:54 
  at Xamarin.Forms.MessagingCenter.InnerSend (System.String message, System.Type senderType, System.Type argType, System.Object sender, System.Object args) [0x00069] in C:\BuildAgent3\work\aad494dc9bc9783\Xamarin.Forms.Core\MessagingCenter.cs:95 
  at Xamarin.Forms.MessagingCenter.Send[TSender] (Xamarin.Forms.TSender sender, System.String message) [0x00013] in C:\BuildAgent3\work\aad494dc9bc9783\Xamarin.Forms.Core\MessagingCenter.cs:23 
  at MobileCRM.Shared.DashboardViewModel+<ExecuteLoadSeedDataCommand>d__6.MoveNext () [0x00a03] in D:\Prj3rd\OndaCRMApp\Client\MobileCRM.Shared\ViewModels\Home\DashboardViewModel.cs:128 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.TaskAwaiter.GetResult () [0x00000] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:113 
  at MobileCRM.Shared.DashboardViewModel+<<get_LoadSeedDataCommand>b__5_0>d.MoveNext () [0x0001f] in D:\Prj3rd\OndaCRMApp\Client\MobileCRM.Shared\ViewModels\Home\DashboardViewModel.cs:45 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (System.Object state) [0x00000] in /Users/builder/data/lanes/2923/52635947/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1018 
  at Android.App.SyncContext+<Post>c__AnonStorey0.<>m__0 () [0x00000] in /Users/builder/data/lanes/3340/4e275588/source/monodroid/src/Mono.Android/src/Android.App/SyncContext.cs:18 
  at Java.Lang.Thread+RunnableImplementor.Run () [0x0000b] in /Users/builder/data/lanes/3340/4e275588/source/monodroid/src/Mono.Android/src/Java.Lang/Thread.cs:36 
  at Java.Lang.IRunnableInvoker.n_Run (IntPtr jnienv, IntPtr native__this) [0x00009] in /Users/builder/data/lanes/3340/4e275588/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Java.Lang.IRunnable.cs:81 
  at (wrapper dynamic-method) System.Object:10380bda-a7f1-45e5-8e3f-7465ce556290 (intptr,intptr)

 

 

 

 

[Ves]

Hi Marco,

Thanks for writing and for the details. Unfortunately, the stack trace does not allow us to pinpoint a possible cause for the exception -- we can see the line in the code, but it is not clear why would a certain reference be null at that point. Can you send us a small sample, which reproduces the problem, so that we can investigate? Looking forward to hearing from you.

Best regards,
Ves
Telerik