Resource key not found during runtime?

Question

I have a rather peculiar problem with one of my WPF applications:

I declared a ControlTemplate as static resource and I can use it inside the Visual Studio Designer - at runtime however, the resource cannot be found.

My WPF code (shortened):

<Window xmlns:PlatformUI="clr-namespace:Microsoft.Internal.VisualStudio.PlatformUI;assembly=Microsoft.VisualStudio.Shell.12.0" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        ...
        x:Class="U6656.WebWindow"
        ... >
    <Window.Resources>
        <ControlTemplate x:Key="tmplt" x:Name="tmplt" TargetType="Label">
            <Label .... >
                ....
            </Label>
        </ControlTemplate>
    </Window.Resources>
    <Grid>
        <Label x:Name="lb_test" Template="{StaticResource tmplt}"/>
    </Grid>
</Window>

As mentionend - It works perfectly inside the designer and compiles without problem.
However, I get a XAMLParseException (the underlying exception is a KeyNotFoundException).

---

I also tried the following (still without any luck):

• I removed the Template={...}-Attribute from my Label

• I added the following code after my InitializeComponent()-call:

  lb_test.Template = this.TryFindResource("tmplt") as ControlTemplate;

And now comes the really odd part:
IntelliSense indicates, that the Field this.Resources is not empty - moreover: it has exactly the resources it should have. Nevertheless - the small line above fails again with a KeyNotFoundException.

---

EDIT №1: Here is the Exception dump:

System.Collections.Generic.KeyNotFoundException wurde nicht behandelt.
  HResult=-2146232969
  Message=Der angegebene Schlüssel war nicht im Wörterbuch angegeben.
  Source=PresentationFramework
  StackTrace:
       bei System.Windows.Baml2006.Baml2006SchemaContext.GetDependencyProperty(Int16 propertyId)
       bei System.Windows.Baml2006.Baml2006Reader.Process_PropertyWithExtension()
       bei System.Windows.Baml2006.Baml2006Reader.Process_OneBamlRecord()
       bei System.Windows.Baml2006.Baml2006Reader.ReadObject(KeyRecord record)
       bei System.Windows.ResourceDictionary.CreateObject(KeyRecord key)
       bei System.Windows.ResourceDictionary.OnGettingValue(Object key, Object& value, Boolean& canCache)
       bei System.Windows.ResourceDictionary.OnGettingValuePrivate(Object key, Object& value, Boolean& canCache)
       bei System.Windows.ResourceDictionary.GetValueWithoutLock(Object key, Boolean& canCache)
       bei System.Windows.ResourceDictionary.GetValue(Object key, Boolean& canCache)
       bei System.Windows.ResourceDictionary.get_Item(Object key)
       bei U6656.WebWindow..ctor()
       bei U6656.App.InnerStartUp(StartupEventArgs e)
       bei U6656.App.OnStartup(StartupEventArgs e)
       bei System.Windows.Application.<.ctor>b__1(Object unused)
       bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
       bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
       bei System.Windows.Threading.DispatcherOperation.InvokeImpl()
       bei System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
       bei System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       bei System.Windows.Threading.DispatcherOperation.Invoke()
       bei System.Windows.Threading.Dispatcher.ProcessQueue()
       bei System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       bei MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       bei MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
       bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
       bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
       bei System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
       bei MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
       bei MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
       bei System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
       bei System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
       bei System.Windows.Threading.Dispatcher.Run()
       bei System.Windows.Application.RunDispatcher(Object ignore)
       bei System.Windows.Application.RunInternal(Window window)
       bei System.Windows.Application.Run(Window window)
       bei System.Windows.Application.Run()
       bei U6656.App.Main()
  InnerException: 

EDIT №2: When using IntelliSense to observe the value of this.Resources, I get the following Exception:

XAML-Knotenstream: StartObject fehlt vor StartMember
"System.Windows.Controls.ContentControl.Content".

which means

XAML node stream: StartObject is missing before StartMember
"System.Windows.Controls.ContentControl.Content".

Answer 1

I solved it myself by using a UserControl instead of templated controls.

Answer 2

I had a KeyNotFoundException with a control template defined in generic.xaml

Exception thrown: 'System.Collections.Generic.KeyNotFoundException' in PresentationFramework.dll Exception thrown: 'System.Xaml.XamlObjectWriterException' in System.Xaml.dll Exception thrown: 'System.Windows.Markup.XamlParseException' in PresentationFramework.dll

Switching from a TemplateBinding to Binding RelativeSource={RelativeSource TemplatedParent} resolved the issue.