Fix STATUS_MUI_FILE_NOT_LOADED 0XC00B0006 error

You'll see this error code 0XC00B0006 when Windows tries to load a user interface string for a specific language but can't find the matching .mui file in the resource cache. It happens a lot after a Windows Update that added or updated a language pack, or when you install a new app in a non-English locale. The system checks its cache first, and if the entry's missing or corrupted, it throws this error and the app might crash or display garbled text.

The root cause is simple: the resource loader cache in the registry or on disk doesn't have a loaded Multilingual User Interface (MUI) entry for the language requested. This can happen if the language pack wasn't fully installed, if you uninstalled a language but left orphaned references, or if a disk cleanup tool deleted files inside C:\Windows\System32\en-US (or your locale folder). The cache itself lives in the registry under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MUI\UILanguages and in the %SystemRoot%\System32\ directory structure.

Real-world trigger: I've seen this most often after a user adds Japanese or Arabic as a display language, runs Windows Update, and then removes the language pack manually without using the proper Settings app. The cache entries persist but the actual .mui files are gone.

Fix: Rebuild the MUI cache and repair system files

Open Command Prompt as Administrator. Press the Windows key, type cmd, right-click Command Prompt, and select Run as administrator. Click Yes on the UAC prompt.
Run the System File Checker. Type this command and press Enter:
```
sfc /scannow
```
Wait for it to finish—this can take 10 to 15 minutes. You'll see a message like "Windows Resource Protection found corrupt files and successfully repaired them." If it says it couldn't fix something, move to step 3.
Run DISM to fix the component store. Type this and press Enter:
```
DISM /Online /Cleanup-Image /RestoreHealth
```
This takes 15 to 20 minutes. Keep the window open and don't close it. After it's done, restart your computer. You should see the error disappear.
If the error persists, clear the registry cache. Open Regedit by pressing Windows key + R, typing regedit, and pressing Enter. Navigate to:
```
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MUI\UILanguages
```
Right-click the subkey for the language that's failing (like ja-JP or ar-SA), and choose Export to back it up. Then delete that subkey. Close Regedit.
Re-add the language pack through Settings. Go to Settings > Time & Language > Language & region. Under Preferred languages, click Add a language. Choose the same language you removed (e.g., Japanese), install it completely, then restart again. This rebuilds both the cache and the actual files.

What to check if the error still shows up

If you've done all that and the error code still pops up in Event Viewer or a program still crashes, look at these two things:

Check if the .mui file exists. Go to C:\Windows\System32\ (like C:\Windows\System32\fr-FR). If that folder is empty or missing entirely, copy the .mui files from a working machine with the same Windows version and language pack. You can also run dism /online /add-package with the correct .cab file from the Microsoft Update Catalog, but that's an advanced step—I'd recommend just reinstalling the language pack from Settings instead.
Run the Windows Update troubleshooter. Sometimes a pending update is blocking the cache rebuild. Open Settings > Update & Security > Troubleshoot > Additional troubleshooters > Windows Update. Run it, apply any fixes, then restart and try the steps above again.

Most of the time, the SFC and DISM combo nails it. If you're unlucky and it's a broken registry reference from an uninstall, deleting the key and reinstalling the language pack is the only clean fix. Don't bother reinstalling Windows—that's overkill for a missing cache entry.