PreviewKeyDown events of TextBox controls aren't triggered by Microsoft IME in WPF apps

Note

The issue that's discussed in this article is a bug in Windows 10, versions 2004, 20H2, 21H1, and 21H2. This bug isn't fixed in Windows 10, but it is fixed in Windows 11. To avoid the issue, you can upgrade your system to Windows 11.

This article discusses an issue that prevents PreviewKeyDown events of TextBox controls from being triggered by some Microsoft input method editors (IMEs) in Windows Presentation Foundation (WPF) applications.

Applies to: Windows Presentation Foundation, Windows 10, version 2004, Windows 10, version 20H2, Windows 10, version 21H1, Windows 10, version 21H2

Symptoms

Consider the following scenario:

1. You run a WPF application in Windows 10, version 2004, 20H2, 21H1, or 21H2.
2. You enter text into a TextBox control by using a Microsoft IME of East Asia.

In this scenario, the PreviewKeyDown event of the control isn't triggered. Therefore, some functions of the application that depend on the PreviewKeyDown event handlers don't work as expected.

Cause

Microsoft IMEs are updated in some versions of Windows 10. This issue occurs when you use some of the latest Microsoft IMEs.

Solution

Turn on the Compatibility option to revert to the previous version of Microsoft IME. To do this, follow these steps:

1. Select Start, enter language settings, and then select Language settings in the list of results.

   

2. Select the Language options icon (ellipses) for your language.

   

3. On the Options page, select Options for the IME that you're using.

   

4. Select General.

   

5. Turn on the Use previous version of <YourIME> option, and then select OK in the window that opens.