Null reference exception when running a .NET app with UI automation
This article helps you resolve the null reference exception that's thrown when you run a .NET application with UI automation.
Original product version: Microsoft .NET Framework
Original KB number: 2653004
Symptoms
You may see a null reference exception thrown when running an application that contains a .NET Calendar control and any UI automation tool like Inspect.exe. The application may crash when focus goes to the Calendar control.
Cause
You may have a subtle issue in your app defined template where the null values in the AutomationPeer
collection stemmed.
The resources within a theme level dictionary that will be referenced outside need to be named using a ComponentResourceKey
. In this case, UIAutomation (Inspect.exe) wants to reference this DataTemplate
and raise the exception.
Resolution
Set the DataTamplate
Key
as follows:
<DataTemplate x:Key="{ComponentResourceKey TypeInTargetAssembly=CalendarItem, ResourceId=DayTitleTemplate}">
Instead of:
<DataTemplate x:Key="DayTitleTemplate">
Feedback
https://aka.ms/ContentUserFeedback.
Coming soon: Throughout 2024 we will be phasing out GitHub Issues as the feedback mechanism for content and replacing it with a new feedback system. For more information see:Submit and view feedback for