Fix NS_E_NOT_CONTENT_PARTNER_TRACK 0XC00D135A

Quick answer

Delete the corrupted DRM license files in %PROGRAMDATA%\Microsoft\Windows\DRM and re-add the track to your library.

What's actually happening here

Windows Media Player (WMP) uses a DRM system called Windows Media DRM (WMDRM) to enforce licensing for protected content. When you get NS_E_NOT_CONTENT_PARTNER_TRACK (0XC00D135A), WMP is telling you it found a media file flagged as protected but can't locate the corresponding license or identify the content provider that issued it. This happens most often with old WMA or ASF files that were purchased from stores like MSN Music or Napster back in the 2000s, or with files that had their DRM headers corrupted during transfer or compression.

The error isn't about the file itself being broken — it's about the metadata that says "this file needs a license" being present without any way to resolve that license. WMP checks a local license store, and if the provider ID baked into the file doesn't match any known provider, it throws this error.

Step-by-step fix

Close Windows Media Player entirely. Make sure no WMP process is running in Task Manager.
Open File Explorer and paste this into the address bar:
```
%PROGRAMDATA%\Microsoft\Windows\DRM
```
Hit Enter. This folder is hidden by default — if you can't see it, enable hidden items in View settings.
Delete everything inside that folder. You'll see files like drmv2.key, drmc.reg, and some temp files. Don't delete the folder itself, just its contents. You might get a permissions warning for one or two files — skip those.
Restart Windows Media Player. It'll rebuild the DRM store fresh. Go to your library and try playing the problem file again.
If it still fails, right-click the file in WMP, select Delete (which removes it from the library but not from disk), then drag it back into the library from Explorer.

Alternative fixes if the main one doesn't work

Sometimes the file's DRM headers are too mangled even after rebuilding the license store. Here's what else you can try:

Convert the file to MP3 or AAC using a tool like ffmpeg. This strips the DRM flag entirely. The command to convert a WMA to MP3:
```
ffmpeg -i input.wma -c:a libmp3lame -q:a 2 output.mp3
```
The -q:a 2 gives VBR ~190 kbps. If ffmpeg reports a bogus stream, use -bitexact to override.
Use the Windows Media Player Troubleshooter built into Windows 10/11. Search for "Find and fix problems with playing audio" in Settings. It resets WMP's DRM components and re-registers DLLs. Worth a shot but rarely fixes this specific error alone.
Reinstall the codec pack if you're using third-party codecs. Sometimes a mucked-up codec chain confuses WMP's DRM parser. Uninstall any codec pack, then install the latest K-Lite Codec Pack Basic and see if WMP re-handles the file.

Prevention tip

The simplest way to avoid this error forever: don't rely on WMP's DRM. If you're ripping CDs or storing personal media, use MP3 or FLAC without any DRM wrapper. For older purchased content, check if the store still provides a license manager — most shut down years ago. Running del /f /q "%PROGRAMDATA%\Microsoft\Windows\DRM\*.*" in an admin command prompt after each major Windows update clears stale license data before it causes playback issues.