NS_E_DRM_BUFFER_TOO_SMALL Fix: Windows Media Player Error 0XC00D275C

Solution 1: Restart Windows Media Player (30 seconds)

I know this error is infuriating because it looks complicated, but the most common trigger is a simple memory hiccup. The DRM buffer is a tiny chunk of RAM Windows Media Player uses to store protected content while it's playing. If the player's been running for a while or you've had several files open, that buffer can get bogged down.

Here's what you do:

1. Close Windows Media Player completely. Don't just hit the X — check the system tray for the WMP icon and right-click it, then choose Exit.
2. Wait 10 seconds, then reopen the file.

If that doesn't work, try playing a different DRM-protected file. If the error only shows on one specific file, the file itself might be corrupted, not your system. That's a separate problem, but the reset in Solution 3 often clears it.

Skip this step if you've already restarted the player and it didn't help. Move on to the next fix.

Solution 2: Update Codecs and Windows (5 minutes)

This tripped me up the first time too — I spent an hour digging into DRM settings when the real culprit was an outdated codec. Windows Media Player relies on codecs to decode the audio and video streams inside DRM-protected files. If a codec is old or missing, the player throws a buffer error because it can't process the data correctly.

Here's how to check:

1. Open Windows Media Player.
2. Press Alt+H to open the Help menu, then select About Windows Media Player.
3. If you see something like Codec error next to any audio or video format, you need to update.

But honestly, the easiest path is just to run Windows Update. Microsoft pushes codec updates through it, and manual codec downloads often cause more problems than they solve.

Start > Settings > Windows Update > Check for updates

Let it install everything, then restart your PC. Try the file again.

Also, if you've recently installed a third-party codec pack (like K-Lite), try uninstalling it. I've seen those conflict with WMP's internal DRM handling more times than I can count. The built-in codecs are fine for most files.

Solution 3: Reset DRM Folder (15+ minutes)

This is the nuclear option, but it's the one that actually fixes the root cause in most cases. Windows stores DRM licenses and player settings in a hidden folder called DRM. Over time, that folder gets corrupted — maybe from a bad update, a crash, or an antivirus scan that quarantined a file. When that happens, the player can't allocate buffers correctly, and you get error 0XC00D275C.

Resetting the folder forces Windows to rebuild it from scratch. You'll lose any DRM licenses you've purchased, which means you might need to re-download or re-authorize some files. But if you're staring at this error, you probably can't play those files anyway, so it's not a big loss.

Here's the process:

1. Close Windows Media Player and make sure it's not running in the background (check Task Manager).
2. Open File Explorer and go to %PROGRAMDATA%\Microsoft. You can paste that directly into the address bar.
3. Look for a folder named DRM. Right-click it and choose Rename. Change it to DRM.old.
4. Now open the Registry Editor. Press Win+R, type regedit, and hit Enter.
5. Navigate to HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer.
6. Right-click the MediaPlayer key, select Delete, and confirm. This resets the player's settings, including DRM state.

Warning: Deleting registry keys is safe here, but don't go deleting anything else. Stick to the exact key I listed.

7. Restart your PC. Windows will create a fresh DRM folder and MediaPlayer key on next launch.
8. Open Windows Media Player and try your file. You'll likely get a prompt to re-acquire licenses — that's normal.

If the error persists after this, try the same rename trick but look for a DRM folder under C:\Users\[YourUsername]\AppData\Local\Microsoft as well. Some Windows versions store a secondary copy there.

One more thing — if you're using a corporate laptop with managed DRM policies, this reset might not work because group policy will recreate the same broken state. In that case, talk to your IT admin. They'll need to push a policy refresh or reissue licenses.

Why this error happens

The DRM buffer is a fixed-size memory allocation that Media Player uses to hold decrypted content. When the DRM system gets confused — usually due to corrupted license stores or failed update — it miscalculates the buffer size and throws 0XC00D275C. That's why a simple restart helps sometimes, but a full reset is the only lasting cure.

I've also seen this error pop up when playing files from network drives or USB sticks with slow read speeds. The player asks for more buffer than the system can allocate because the file stream is stuttering. Copy the file to your local hard drive and try again — that's a free test that takes 10 seconds.

If you've gone through all three solutions and still get the error, let me know in the comments what step you're stuck on. I'll help you dig deeper.