Value cannot be null exception

Docking/MDI for WPF Forum

The latest build of this product (v2019.1 build 0685) was released 2 months ago, which was before this thread was created.
Posted 14 days ago by Martin Votruba
Version: 17.2.0685
Platform: .NET 4.5
Environment: Windows 10 (64-bit)
Avatar

Hello,

I am using yours Docking component and after some change in the code I have done recently, a unhandled exception started to be raised when the applicaiton is run for some time. The exception is raised quite irregualry and thus I have not been able so far to observe the exception while debugging and all I have is the stack trace. I do not expect that you will be able to identify the exact cause of this exception, howerver I will highly appraciate any suggestions, what might be the cause. Even some explonation of what the DockingWindowContainerBaseAutomationPeer.GetChildrenCore() is doing might help to locate the bug.

An unhandled exception occurred: Value cannot be null.
Parameter name: element
at System.Windows.Automation.Peers.UIElementAutomationPeer.CreatePeerForElement(UIElement element)
at ActiproSoftware.Windows.Controls.Docking.Automation.Peers.DockingWindowContainerBaseAutomationPeer.GetChildrenCore()
at System.Windows.Automation.Peers.AutomationPeer.EnsureChildren()
at System.Windows.Automation.Peers.AutomationPeer.UpdateChildrenInternal(Int32 invalidateLimit)
at System.Windows.Automation.Peers.AutomationPeer.UpdateChildren()
at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
at System.Windows.ContextLayoutManager.fireAutomationEvents()
at System.Windows.ContextLayoutManager.UpdateLayout()
at System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)
at System.Windows.Media.MediaContext.InvokeOnRenderCallback.DoWork()
at System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)

Thank you very much,

Martin

Comments (1)

Posted 14 days ago by Actipro Software Support - Cleveland, OH, USA
Avatar

Hello,

I'm sorry you're having trouble.  I see you are using our 2017.2 version.  Looking at our code notes, I believe this bug was fixed in the 2018.1 version.


Actipro Software Support

Add Comment

Please log in to a validated account to post comments.