Fix NS_E_UNSUPPORTED_LANGUAGE (0XC00D145C) in Windows

You hit the NS_E_UNSUPPORTED_LANGUAGE error and it’s annoying — especially when you just want to play a song or video.

I’ve seen this in Windows Media Player, Groove Music, and even some older media apps. The real fix is simple: change your system locale. Don’t waste time reinstalling codecs or your media player — that won’t touch this problem.

The fix: change your system locale to match the media file’s language

Open the Control Panel. Fastest way: press Windows Key + R, type control, hit Enter.
Click Clock and Region. If you’re in icon view, skip this — you’ll see Region directly.
Click Region.
Go to the Administrative tab.
Under “Language for non-Unicode programs,” click Change system locale. After clicking, you’ll see a list of languages.
Select the language that matches your file. For example, if your video has Russian audio, pick Russian (Russia). If it’s a Japanese file, pick Japanese (Japan).
Click OK. Windows will ask to restart your computer. Do it. After restarting, the locale change takes effect.
Try playing the media file again. It should work now.

That’s it. No registry edits, no codec packs. Just a locale switch.

Why this works

The NS_E_UNSUPPORTED_LANGUAGE error means Windows Media Player or the media framework (Media Foundation) can’t find the language handler for the audio or subtitle track in your file. Media files often embed language tags — think of them as labels saying “this track is in Spanish” or “this track is in French.” Windows reads that tag, then looks for the matching language support in your system. If your system locale is set to English (United States) and the file says “Russian,” Windows doesn’t have the language module ready. Changing the system locale tells Windows to load that language’s support at boot. It’s a blunt fix, but it always works for this specific error.

One thing I want to be clear about: this doesn’t change your display language or keyboard layout. It only changes how Windows handles non-Unicode programs. That’s why your menus stay in English while Russian audio suddenly plays fine.

Less common variations of the same issue

Sometimes the error shows slightly different symptoms:

Error appears only for subtitles, not audio. Same fix. The subtitle track has a language tag Windows can’t handle. Change locale, restart.
Error happens in a specific app like MPC-HC or VLC. Those players use their own codec pipelines, but if they rely on Windows Media Foundation instead of internal decoders, the locale change still works. Try it before messing with VLC settings.
Error on modern apps like Films & TV or Groove Music. These use Media Foundation natively. Same fix applies directly.
Error after Windows update. Updates sometimes reset region settings or locale preferences. Check your system locale — it might have reverted to a default. Change it back.
Error on Windows Server editions. Server doesn’t always install language packs by default. You’ll need to go to Language and Region settings, add the language, and install the pack. Then change locale.

Prevention: stop this error from coming back

If you regularly play media in multiple languages — like anime with Japanese audio, or European films with French tracks — you have two choices:

Keep the system locale set to the most common language you use. Switch only when needed. A bit tedious, but it works.
Install all the language packs you need. Go to Settings > Time & Language > Language & Region. Add the languages you need (e.g., Japanese, Russian, French). For each one, click the three dots and choose Language options. Then download the Basic typing or Speech pack. This preloads the language modules. After installing, restart. Then change the locale to one of those languages. Now Windows has multiple language handlers active. Some files will work without switching locale — but not all. It’s not a perfect fix, just reduces how often you need to change locale.

Honestly, prevention is a pain here. Microsoft never made multilingual media playback seamless. The real long-term solution: use a player like VLC that handles its own language parsing and ignores Windows locale entirely. VLC never throws NS_E_UNSUPPORTED_LANGUAGE because it doesn’t use Windows Media Foundation. That’s what I do. But if you prefer first-party apps, keep this page bookmarked. You’ll need it again.