.NET Framework Crash occurring while entering the Korean-English Convert key in WPF TextBox

Once enter the Korean-English Convert Key in WPF text box, System.Enviroment.FailFast Exception occurred and Framework crashed. It occurred just once and error message was logged like below. (just 2 logs)

* .NET Runtime Error *

Application: MainFrame.exe
Framework Version: v4.0.30319
Description: The application requested process termination through System.Environment.FailFast(string message).
Message: Unrecoverable system error.
Stack:
   at System.Environment.FailFast(System.String)
   at System.Windows.Documents.TextStore.SetFinalDocumentState(MS.Internal.Documents.UndoManager, System.Collections.Stack, Int32, Int32, Int32, Int32, Int32)
   at System.Windows.Documents.TextStore.HandleCompositionEvents(Int32)
   at System.Windows.Documents.TextStore.GrantLockWorker(LockFlags)
   at System.Windows.Documents.TextStore.RequestLock(LockFlags, Int32 ByRef)
   at MS.Win32.UnsafeNativeMethods+ITfKeystrokeMgr.KeyDown(Int32, Int32, Boolean ByRef)
   at MS.Win32.UnsafeNativeMethods+ITfKeystrokeMgr.KeyDown(Int32, Int32, Boolean ByRef)
   at System.Windows.Input.TextServicesContext.Keystroke(Int32, Int32, KeyOp)
   at System.Windows.Input.TextServicesManager.PostProcessInput(System.Object, System.Windows.Input.ProcessInputEventArgs)
   at System.Windows.Input.InputManager.RaiseProcessInputEventHandlers(System.Windows.Input.ProcessInputEventHandler, System.Windows.Input.ProcessInputEventArgs)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputManager.ProcessInput(System.Windows.Input.InputEventArgs)
   at System.Windows.Interop.HwndKeyboardInputProvider.ReportInput(IntPtr, System.Windows.Input.InputMode, Int32, System.Windows.Input.RawKeyboardActions, Int32, Boolean, Boolean, Int32)
   at System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(System.Windows.Interop.MSG ByRef, Boolean ByRef)
   at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(System.Windows.Interop.MSG ByRef, System.Windows.Input.ModifierKeys)
   at System.Windows.Interop.HwndSource.OnPreprocessMessage(System.Object)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority, System.TimeSpan, System.Delegate, System.Object, Int32)
   at System.Windows.Threading.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority, System.Delegate, System.Object)
   at System.Windows.Interop.HwndSource.OnPreprocessMessageThunk(System.Windows.Interop.MSG ByRef, Boolean ByRef)
   at System.Windows.Interop.ThreadMessageEventHandler.Invoke(System.Windows.Interop.MSG ByRef, Boolean ByRef)
   at System.Windows.Interop.ComponentDispatcherThread.RaiseThreadMessage(System.Windows.Interop.MSG ByRef)
   at System.Windows.Threading.Dispatcher.TranslateAndDispatchMessage(System.Windows.Interop.MSG ByRef)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame)
   at System.Windows.Window.ShowHelper(System.Object)
   at System.Windows.Window.ShowDialog()
   at MainFrame.ModuleGrids.NewWorklistWindow.ShowDialog()
   at MainFrame.ModuleGrids.WorklistGrid.ClickNewPatientButton(System.Object, System.Windows.RoutedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject, System.Windows.RoutedEventArgs)
   at System.Windows.Controls.Button.OnClick()
   at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(System.Windows.Input.MouseButtonEventArgs)
   at System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate, System.Object)
   at System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.UIElement.ReRaiseEventAs(System.Windows.DependencyObject, System.Windows.RoutedEventArgs, System.Windows.RoutedEvent)
   at System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate, System.Object)
   at System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject, System.Windows.RoutedEventArgs)
   at System.Windows.UIElement.RaiseTrustedEvent(System.Windows.RoutedEventArgs)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.StylusLogic.PromoteMainToMouse(System.Windows.Input.StagingAreaInputItem)
   at System.Windows.Input.StylusLogic.PostProcessInput(System.Object, System.Windows.Input.ProcessInputEventArgs)
   at System.Windows.Input.InputManager.RaiseProcessInputEventHandlers(System.Windows.Input.ProcessInputEventHandler, System.Windows.Input.ProcessInputEventArgs)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputManager.ProcessInput(System.Windows.Input.InputEventArgs)
   at System.Windows.Input.StylusLogic.InputManagerProcessInput(System.Object)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
   at System.Windows.Threading.DispatcherOperation.InvokeImpl()
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.ProcessQueue()
   at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
   at MS.Win32.HwndWrapper.WndProc(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(System.Object)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority, System.TimeSpan, System.Delegate, System.Object, Int32)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr, Int32, IntPtr, IntPtr)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame)
   at System.Windows.Window.ShowHelper(System.Object)
   at System.Windows.Window.ShowDialog()
   at MainFrame.App.ShowMainWindow()
   at MainFrame.App.AppStartUp(System.Object, System.Windows.StartupEventArgs)
   at System.Windows.Application.<.ctor>b__1(System.Object)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
   at System.Windows.Threading.DispatcherOperation.InvokeImpl()
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.ProcessQueue()
   at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
   at MS.Win32.HwndWrapper.WndProc(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(System.Object)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority, System.TimeSpan, System.Delegate, System.Object, Int32)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr, Int32, IntPtr, IntPtr)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame)
   at System.Windows.Application.RunInternal(System.Windows.Window)
   at System.Windows.Application.Run()
   at MainFrame.App.Main()

* Application Error *

Faulting application name: MainFrame.exe, version: 3.3.0.38, time stamp: 0x57f35616
Faulting module name: PresentationFramework.ni.dll, version: 4.0.30319.34209, time stamp: 0x5348b261
Exception Code: 0x80131623
Fault Offset: 0x0000000000d409b8
Faulting process ID: 0x1578
Faulting application start time: 0x01d2245b19cf8521
Faulting application path: D:\Workstation\MainFrame.exe
Faulting module path: C:\windows\assembly\NativeImages_v4.0.30319_64\Presentatio5ae0f00f#\bbb7fc50a73e54c4c8c15f14994f965b\PresentationFramework.ni.dll
Report ID: f929aba1-90ef-11e6-bb64-e4a4719c7bf5

* Environment *

Windows Embedded Standard 7 English

.NET Framework 4.6.1

with Korean IME

I read a post, the Exception Code 0x80131623 means just System.Environment.FailFast Exception. Can anyone provide me the rootcause and solution to this issue?