NS_E_MSAUDIO_NOT_INSTALLED (0XC00D0BB9): MSAudio Codec Missing Fix

Cause 1: A Codec Pack Overwrote the Microsoft Audio Codec

This is the #1 reason you're seeing NS_E_MSAUDIO_NOT_INSTALLED (0XC00D0BB9). What's actually happening here is that a third-party codec pack—usually K-Lite Codec Pack or CCCP—has replaced or deleted the system's wmcodecdsp.dll or msaud2.acm files. Windows Media Player relies on these specific Microsoft-owned codecs. When a third-party pack gives you a different version or removes them, WMP throws this error because it can't find what it expects.

You'll see this most often right after installing or updating a codec pack, or after running a video cleanup tool like Codec Tweak Tool that strips out Microsoft codecs thinking they're duplicates.

The Real Fix: Re-register and Replace the Default Codec

1. Open a Command Prompt as Administrator. Hit Win + X, choose “Terminal (Admin)” or “Command Prompt (Admin)”.
2. Run these commands in order. Each re-registers a core Windows Media codec file:

   regsvr32.exe wmcodecsdk.dll
   regsvr32.exe wmvsenc.dll
   regsvr32.exe wmvdspa.dll
   regsvr32.exe mfplat.dll
   regsvr32.exe wmspdmod.dll

3. Now restore the audio codec specifically:

   regsvr32.exe msaud2.acm

   If you get a “module failed to load” on msaud2.acm, that's your smoking gun—the file is missing or corrupted.
4. If msaud2.acm failed, copy it from a working system or an installation ISO. On Windows 10/11, the file lives at C:\Windows\System32. Grab it from a known-good machine or extract it from the install.wim. Then place it in C:\Windows\System32 and run regsvr32.exe msaud2.acm again.
5. Finally, run the System File Checker to repair any other broken system files:

   sfc /scannow

After these steps, restart WMP and try your audio file. That fixes roughly 80% of cases.

Cause 2: Windows Update Broke the Codec Registration

Less common, but I've seen this on Windows 11 22H2 and 23H2 after cumulative updates. Microsoft occasionally updates mfplat.dll or the Media Foundation framework, and the registration gets scrambled. You'll notice this after a reboot following a Patch Tuesday update.

The Fix: Run Windows Media Player Troubleshooter, Then Re-register

1. Open Settings > System > Troubleshoot > Other troubleshooters. Run the Windows Media Player troubleshooter. It checks for missing codec registration and sometimes applies a fix automatically.
2. If that doesn't cut it, open an admin Command Prompt again and run:

   DISM /Online /Cleanup-Image /RestoreHealth

   This checks the component store for corruption. Let it finish—takes 5–10 minutes.
3. Then re-run the regsvr32 commands from Cause 1. The order matters: run them all again, not just the audio one.
4. Reboot. Test the file.

The DISM step is the key here. It's not just about the codec file itself—it's about the Media Foundation infrastructure that depends on a healthy component store.

Cause 3: The MSAudio Codec Was Never Installed (Clean Windows Install)

On a fresh Windows install, especially if you used a debloater script or a custom ISO like Tiny11, the Windows Media Player and its codecs might be missing entirely. The error code isn't wrong—the codec literally isn't there. You'll see this on a clean system when you try to play an .ac3 or .wma file without ever having launched WMP before.

The Fix: Install the Windows Media Feature Pack

1. Go to Settings > Apps > Optional features. Click “Add a feature”.
2. Search for “Media Feature Pack”. Install it. This is the official way to get the MSAudio codec on a clean system.
3. If you're on Windows 10 N or Windows 11 N edition, you'll need the Media Feature Pack for N editions directly from Microsoft's website. Download and install it.
4. Restart. The codec should be available now.

Note: If you're on a normal Windows Home or Pro edition and the optional feature doesn't appear, you might have a stripped-down image. Run dism /online /get-features /format:table | findstr Media to see if the feature is even present. If it's not listed, your ISO is missing it—grab a fresh one from Microsoft.

Quick-Reference Summary

One last thing: if you've tried all three fixes and still get the error, consider using a different media player like VLC or MPC-HC. They bundle their own codecs and don't depend on the system's MSAudio codec at all. Sometimes the pragmatic fix is to stop fighting Windows Media Player.