an unhandled error has occurred
click here to reload the designer
following is the error details:
Microsoft.Internal.Assumes+InternalErrorException
Internal error occurred. Additional information: ''.
at System.ComponentModel.Composition.Hosting.ImportEngine.InPrerequisiteLoop()
at System.ComponentModel.Composition.Hosting.ImportEngine.TrySatisfyImportsStateMachine(PartManager partManager, ComposablePart part)
at System.ComponentModel.Composition.Hosting.ImportEngine.TrySatisfyImports(PartManager partManager, ComposablePart part, Boolean shouldTrackImports)
at System.ComponentModel.Composition.Hosting.ImportEngine.SatisfyImports(ComposablePart part)
at System.ComponentModel.Composition.Hosting.CompositionServices.GetExportedValueFromComposedPart(ImportEngine engine, ComposablePart part, ExportDefinition definition)
at System.ComponentModel.Composition.Hosting.CatalogExportProvider.GetExportedValue(CatalogPart part, ExportDefinition export, Boolean isSharedPart)
at System.ComponentModel.Composition.Hosting.CatalogExportProvider.CatalogExport.GetExportedValueCore()
at System.ComponentModel.Composition.Primitives.Export.get_Value()
at System.ComponentModel.Composition.ExportServices.GetCastedExportedValue[T](Export export)
at System.ComponentModel.Composition.Hosting.ExportProvider.GetExportedValuesCore[T](String contractName)
at Microsoft.Expression.DesignHost.Isolation.Remoting.Marshaler.EnsureMarshalers()
at Microsoft.Expression.DesignHost.Isolation.Remoting.Marshaler.Marshal[TFrom](TFrom value)
at Microsoft.Expression.DesignHost.Isolation.IsolatedExportProvider.ComposeExportedValue[T](T value)
at Microsoft.Expression.DesignHost.IsolatedDesignerService.CreateLease(IIsolationTarget isolationTarget, CancellationToken cancelToken, DesignerServiceEntry& entry)
at Microsoft.Expression.DesignHost.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo(CancellationToken cancelToken)
at Microsoft.Expression.DesignHost.Isolation.IsolatedTaskScheduler.InvokeWithCulture[T](CultureInfo culture, Func`2 func, CancellationToken cancelToken)
at Microsoft.Expression.DesignHost.Isolation.IsolatedTaskScheduler.<>c__DisplayClassa`1.<StartTask>b__6()
at System.Threading.Tasks.Task`1.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
......i tried a lot but unable to reload the designer ...please help ...