dotnet/wpf · error · ArgumentException

SR.Mismatched_RoutedEvent

Error message

SR.Mismatched_RoutedEvent

What it means

The RoutedEventArgs being raised does not match the RoutedEvent of the route it is being sent through. UIElement's raise-impl validates args.RoutedEvent == route.RoutedEvent and throws ArgumentException(SR.Mismatched_RoutedEvent) otherwise. This guards against routing an event instance through an unrelated event definition.

Solutions

  1. Ensure args.RoutedEvent equals the RoutedEvent passed/used for raising; create a new RoutedEventArgs for the correct event
  2. Stop sharing RoutedEventArgs instances across different events
  3. Fix the RoutedEvent reference (copy-paste/rename bug) in the RaiseEvent call

Example fix

// before
var args = new RoutedEventArgs(OtherEvent);
element.RaiseEvent(MyEvent, args); // mismatch
// after
var args = new RoutedEventArgs(MyEvent);
element.RaiseEvent(MyEvent, args);
Defensive patterns

Strategy: validation

Validate before calling

if (args.RoutedEvent != route.RoutedEvent) throw new InvalidOperationException("RoutedEvent mismatch before RaiseEvent");
element.RaiseEvent(args);

Type guard

static bool MatchesRoute(RoutedEvent routeEvent, RoutedEventArgs args) => args?.RoutedEvent == routeEvent;

Try / catch

try { element.RaiseEvent(args); }
catch (ArgumentException ex) when (ex.Message.Contains("RoutedEvent")) { log.Warn("Event/args mismatch", ex); }

Prevention

When it happens

Trigger: Reusing a cached RoutedEventArgs (or args from another event) with a different RoutedEvent; passing the wrong RoutedEvent to RaiseEvent; custom routing code pairing a route with foreign args.

Common situations: Pooled/shared RoutedEventArgs instances after refactoring event definitions; copy-pasted RaiseEvent calls where the event field was renamed; framework code routing through EventRoute manually.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/5bc8a6ac4dae2ec4. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/UIElement.cs:1649

        {
//             VerifyAccess();
            ContextLayoutManager.From(Dispatcher).UpdateLayout();
        }

        internal static void BuildRouteHelper(DependencyObject e, EventRoute route, RoutedEventArgs args)
        {
            ArgumentNullException.ThrowIfNull(route);

            ArgumentNullException.ThrowIfNull(args);

            if (args.Source == null)
            {
                throw new ArgumentException(SR.SourceNotSet);
            }

            if (args.RoutedEvent != route.RoutedEvent)
            {
                throw new ArgumentException(SR.Mismatched_RoutedEvent);
            }

            // Route via visual tree
            if (args.RoutedEvent.RoutingStrategy == RoutingStrategy.Direct)
            {
                UIElement uiElement = e as UIElement;
                ContentElement contentElement = null;
                UIElement3D uiElement3D = null;

                if (uiElement == null)
                {
                    contentElement = e as ContentElement;

                    if (contentElement == null)
                    {
                        uiElement3D = e as UIElement3D;
                    }
                }

View on GitHub (pinned to 81131a70a4)