Fix NS_E_INTERFACE_NOT_REGISTERED_IN_GIT (0XC00D126A)

What's this error and when does it happen?

You're trying to play a video or audio file in Windows Media Player, and instead of playing, you get a pop-up with NS_E_INTERFACE_NOT_REGISTERED_IN_GIT (0XC00D126A). This usually happens right after a Windows update, or after installing/uninstalling some third-party media software that messed with Windows Media Player's COM components. It can also show up if you've been messing with system files or disabling services.

The core problem: Windows Media Player is trying to talk to a COM interface that's supposed to be registered in the Global Interface Table (GIT), but it isn't. The system can't find it, so it gives up. Don't worry — we can fix this without reinstalling Windows.

I'll walk you through three tiers of fixes. Start with the first one. If it doesn't work, move to the next. You can stop as soon as the error's gone.

Fix 1: Quick 30-second restart + DLL re-register

This is the 'did you try turning it off and on' of COM errors, but with a twist. Sometimes the GIT registration just gets stale after a Windows update or a crash.

Close Windows Media Player completely. Check your system tray (bottom-right) to make sure it's not minimized.
Press Win + R to open the Run dialog.
Type cmd and press Ctrl + Shift + Enter to run Command Prompt as administrator. Click Yes on the UAC prompt.
In the black window, type the following and press Enter after each line:
```
regsvr32 wmploc.dll
regsvr32 wmp.dll
regsvr32 wmpps.dll
regsvr32 wmpshell.dll
```
Each one should give you a success message: 'DllRegisterServer in [filename] succeeded.' If you get any error, note it down but continue with the rest.
Restart your computer. Don't skip the restart — it forces Windows to reload these DLLs from scratch.

What to expect after this: When you log back in, open Windows Media Player and try playing the same file. If the error's gone, you're done. If you still see 0XC00D126A, move to Fix 2.

Fix 2: Moderate 5-minute fix — Run SFC and DISM

If the DLL re-register didn't cut it, the issue might be deeper — corrupted system files. Windows has built-in tools to fix those. This takes about 5 minutes, maybe a bit more if your drive is slow.

Open Command Prompt as administrator again (same steps as Fix 1).
First, run the System File Checker. Type:
```
sfc /scannow
```
and press Enter. This will scan all protected system files and replace any that are corrupted. Let it finish — it can take 5–10 minutes. You'll see a progress bar. Don't close the window.
When SFC is done, it'll tell you one of three things:
- 'Windows Resource Protection did not find any integrity violations.' — Good, no corrupted files.
- 'Windows Resource Protection found corrupt files and successfully repaired them.' — Great, but reboot before testing.
- 'Windows Resource Protection found corrupt files but was unable to fix some of them.' — Then we need DISM.
If SFC found problems it couldn't fix, or if the error persists after a reboot, run DISM (Deployment Image Servicing and Management). In the same admin Command Prompt, type:
```
DISM /Online /Cleanup-Image /RestoreHealth
```
and press Enter. This will scan your Windows image and fix any component store corruption. It can take 15–20 minutes. Let it run.
After DISM completes, run sfc /scannow one more time to ensure everything's consistent.
Restart your computer.

What to expect after this: Open Windows Media Player and try to play the file. If the error's gone, fantastic. If not, we have one more fix that's more involved but almost always works.

Fix 3: Advanced 15+ minute fix — Reinstall Windows Media Player via Windows Features

This is the nuclear option for this specific error, but it's not a full Windows reinstall. We're just going to uninstall and reinstall Windows Media Player itself. This forces Windows to re-register all the COM interfaces and GIT entries from scratch.

Important note for Windows 10/11 users: You can't just download a new version of Windows Media Player. It's built into Windows, and you need to toggle it off and on through 'Turn Windows features on or off'.

Press Win + R, type control, and press Enter to open Control Panel.
Click 'Programs' (or 'Programs and Features' if you're in icon view).
On the left side, click 'Turn Windows features on or off'. A list box opens.
Scroll down until you see 'Media Features'. Click the plus sign (+) to expand it.
You'll see 'Windows Media Player' listed with a checkbox. Uncheck it. A warning pops up: 'Turning off Windows Media Player might affect other Windows features...' Click Yes.
Click OK. Windows will apply the changes. You may need to restart. Do it.
After restart, go back to the same 'Turn Windows features on or off' window.
Check the box for 'Windows Media Player' again. Click OK.
Windows will reinstall it. Another restart may be needed.
After the final restart, open Windows Media Player. It might ask you to set up some initial settings (like file associations). Go through that.

What to expect after this: Try playing the file that gave you the error. It should work now. This fix re-registers every COM component that Windows Media Player relies on, including the GIT entries.

If none of these work

If you've done all three fixes and still get 0XC00D126A, there's a chance the problem isn't with Windows Media Player itself, but with a specific codec or third-party plugin that's conflicting. Try playing a different file format — say, a plain .wav file or an .mp3 you know works elsewhere. If those play fine, the issue is with the codec for whatever format you're trying to play. In that case, install a codec pack like K-Lite Codec Pack (Standard is enough) and see if that resolves it.

Also, check if you're running Windows Media Player on a system that's had its 'Media Foundation' components disabled via Group Policy or registry tweaks. That's rare, but I've seen it. If you suspect that, run gpedit.msc (Pro/Enterprise editions only) and look under Computer Configuration > Administrative Templates > Windows Components > Windows Media Player. Make sure nothing is set to 'Disabled' that shouldn't be.

That's it. Start at Fix 1, work your way down. You'll get this sorted.