Fix NS_E_DRM_MONITOR_ERROR (0XC00D273E) on Windows

This error hits when Windows Media Player or a DRM'd file can't talk to the DRM monitor service. Usually after a failed update or corrupt license store.

When This Error Shows Up

You're trying to play a downloaded movie, a purchased music file, or maybe an old Windows Media Player stream. Then boom — a popup with NS_E_DRM_MONITOR_ERROR and the hex code 0XC00D273E. The file won't play. Sometimes it happens right after a Windows Update or a system restore. I've seen it on Windows 10 and 11, but it also crops up on older versions like 8.1. The trigger is almost always a corrupt or missing DRM license store.

What's Actually Wrong

DRM (Digital Rights Management) is a Windows component that checks if you're allowed to play protected content. It talks to a hidden service called the DRM monitor, which validates licenses on the fly. When that service can't start — or the license store gets scrambled — you get this error. The root cause is usually one of two things:

Corrupt license files — They get damaged by a bad update, a crash, or even antivirus software that quarantines part of the DRM system.
Service not running — The DRM monitor service (msvsmon.exe or similar) is disabled or failed to start. This happens more than you'd think after a Windows feature update.

Skip trying to reinstall Windows Media Player — that's a waste of time. The real fix is resetting the DRM store.

How to Fix It

Step 1: Kill the DRM Process

Open Task Manager (Ctrl+Shift+Esc), go to the Details tab, and look for any process named msvsmon.exe, drmupdate.exe, or wmplayer.exe. Right-click each and choose End Task. This clears any stuck state.

Step 2: Reset the DRM License Store

Press Win + R, type %windir%\system32\DRM, and hit Enter. You'll see a folder with cryptic .drm files. Don't delete anything yet. Instead, rename the whole folder to DRM.old. Windows will recreate a fresh store next time you play a protected file.

ren "C:\Windows\System32\DRM" "C:\Windows\System32\DRM.old"

If you get a permissions error, take ownership of the folder first. Right-click it, go to Properties > Security > Advanced, and set yourself as owner. Then do the rename.

Step 3: Restart the DRM Service

Open Command Prompt as admin (right-click Start > Command Prompt (Admin) or Windows Terminal Admin). Run:

net stop msvsmon
net start msvsmon

If the service doesn't exist, don't panic — it's called differently in some builds. Check Services.msc for anything named "DRM Monitor" or "Windows Media Player Network Sharing Service". You want the one that references DRM. Set it to Automatic and start it.

Step 4: Re-register DRM DLLs

Still failing? Register the core library manually. In the same admin Command Prompt, type:

regsvr32 drmupd.exe /s
regsvr32 msvidctl.dll /s
regsvr32 wmdrmsdk.dll /s

Ignore any "entry point not found" errors — those aren't fatal here.

Step 5: Test with a Different File

Try playing a different protected file. If it works, the original file's license is toast. You'll need to redownload it. If it still fails, reboot and try step 2 again — sometimes the rename doesn't stick because of a file lock.

If It Still Fails

Some stubborn cases require a full Windows Media Player reset. Go to Settings > Apps > Optional Features, find Windows Media Player, and uninstall it. Restart, then reinstall it from the same menu. Or use the classic Control Panel: Turn Windows features on or off, uncheck Media Features, reboot, then recheck it. This nukes the DRM store completely.

Had a client last month whose DRM folder was corrupted by a bad third-party codec pack. Uninstalling the codec pack and running the steps above fixed it. If you've installed any sketchy audio/video tools, remove them first.

If you're on an enterprise network, group policy might have disabled the DRM service. Check with your IT admin — you won't fix that one locally.