Fix ERROR_MUI_INVALID_RC_CONFIG (0X00003AFE) on Windows

Quick Answer

Run DISM /Online /Cleanup-Image /RestoreHealth then sfc /scannow in an elevated command prompt. If that fails, remove and reinstall the problematic language pack via Settings > Time & Language > Language.

Why This Happens

MUI stands for Multilingual User Interface. Windows loads language-specific resource files (like .mui files in System32). The error code 0X00003AFE means the resource configuration is invalid—the file is there, but its structure is wrong or corrupted.

What's actually happening here is that Windows finds the expected MUI file but can't parse it. This typically surfaces when you install a language pack, then uninstall it partially, or when a Windows Update tries to patch a language component and fails halfway. I've seen it most on Windows 10 22H2 and Windows 11 23H2 after a botched feature update.

The real consequence: apps that rely on that language resource crash or won't launch. You'll see the error in Event Viewer or as a pop-up.

Fix Steps

1. Open an elevated Command Prompt. Press Win+X, select Terminal (Admin) or Command Prompt (Admin).
2. Run DISM to fix image corruption. Type:

   DISM /Online /Cleanup-Image /RestoreHealth

   This checks the component store (where MUI files live) and replaces any corrupted files from Windows Update. Takes 5–10 minutes. Don't interrupt it.
3. Run System File Checker. After DISM finishes, run:

   sfc /scannow

   SFC scans protected system files and replaces bad ones. It relies on a clean component store—which is why step 2 must come first.
4. Reboot. Restart your PC. Check if the error reappears.

Alternative Fixes If the Main One Fails

Remove and Reinstall the Language Pack

If DISM and SFC didn't help, the language pack itself is likely toast. Here's the manual way:

1. Go to Settings > Time & Language > Language & region.
2. Under Preferred languages, find the language that's causing trouble (likely your display language).
3. Click the three dots next to it, select Remove.
4. Reboot.
5. Add it back: click Add a language, search for it, install it.
6. Set it as your Windows display language. Log off and back on.

Use PowerShell to Force-Remove a Stuck Language Pack

Sometimes the Settings UI won't let you remove a corrupted pack. Use PowerShell as Admin:

Get-WinUserLanguageList
$langList = Get-WinUserLanguageList
$langList.Remove("en-US")  # Replace en-US with the tag of your broken language
Set-WinUserLanguageList -LanguageList $langList -Force

Replace en-US with your language tag (e.g., ja-JP, de-DE). The -Force flag bypasses warnings. Then re-add the language.

Prevention Tip

Don't install language packs from shady third-party sites. Always use the official Windows Settings app or LTSC ISO sources. If you're on an enterprise environment, push language packs via Group Policy or MDM—never manually copy .cab files into System32. Also, keep Windows Update running; missing cumulative updates often leave MUI files in a half-patched state that triggers this error.

Edge case: If you're running Windows 10 LTSC 2021 or Windows 11 23H2 with a custom layout, the error might come from a badly formed Layout.xml in the provisioning package. Delete the package from C:\Windows\Provisioning\Packages if you know what you're doing.