Fix NS_E_WMPCORE_WMX_ENTRYREF_NO_REF (0XC00D10B4) in Windows Media Player

1. Corrupted Windows Media Player library database

What's actually happening here is that Windows Media Player stores your music library metadata—album art, play counts, playlists—in a set of database files tucked away in %USERPROFILE%\AppData\Local\Microsoft\Media Player. When one of these files gets corrupted (common after a system crash or incomplete shutdown), the player can't resolve links inside playlists and throws the 0XC00D10B4 error.

The fix is to delete those database files and let WMP rebuild them from scratch. You won't lose your actual music files, just your play history and custom playlists.

1. Close Windows Media Player completely.
2. Press Win + R, type %USERPROFILE%\AppData\Local\Microsoft\Media Player, and hit Enter.
3. Select all files and folders inside (Ctrl+A), then delete them. You'll need admin permission for a few—grant it.
4. Restart WMP. It'll feel like a fresh install. Re-add your music folders via Organize > Manage libraries.

The reason step 3 works is that WMP can't function without that database, so it creates a clean one on next launch—no more broken references.

2. Stale or malformed playlist files (.wpl, .m3u, .pls)

Sometimes the problem isn't the library—it's a specific playlist file you're trying to open. The error message literally says an ENTRYREF element (which tells the player where a song lives) has no href attribute. This happens when you move or delete a media file that a playlist points to, or when a playlist was created by a buggy third-party app that wrote bad XML.

To track down the culprit:

1. Open WMP, go to the Play tab, and look at the list of playlists on the left pane.
2. Right-click each playlist and choose 'Open file location'—this works for .wpl files saved in your Music folder.
3. Open the playlist in Notepad. Look for lines like <ENTRYREF> without a matching href= attribute. If you see something like <ENTRYREF></ENTRYREF>, that's your problem.
4. Delete that playlist file (or back it up first, then delete).

Skipping this step means the error keeps popping up every time WMP tries to load that playlist. Don't bother editing the XML to add a missing href—you'd have to guess the original path, which is slower than just rebuilding the playlist.

3. Restricted permissions on the playlist folder

Less common, but I've seen this on corporate laptops or after moving user folders. If WMP can't read the playlist directory (due to NTFS permissions), it may still try to parse partial data—and fail with this exact error.

Quick test: try opening the playlist from a different location, like copying it to your Desktop. If it works there, permissions are the issue.

1. Right-click the folder containing your playlists (usually %USERPROFILE%\Music\Playlists), choose Properties > Security tab.
2. Click 'Edit', select your username, and check 'Full control' under Allow.
3. Apply the change, then try WMP again.

The reason this works: WMP runs under your user account. If it can't read the folder metadata, it misreads the playlist structure and drops the href.

4. (Unlikely) Corrupted codec or third-party shell extension interfering

I'm including this only for completeness—it's rare. Some buggy codec packs (like old versions of K-Lite) install shell extensions that intercept media file requests and mangle the path before WMP sees it. You'd also see this error randomly on different playlists.

Test: temporarily disable all non-Microsoft shell extensions using ShellExView (free tool). If the error stops, you've found your culprit. Re-enable extensions one by one to identify the bad actor.

Quick-reference summary