Windows Media Player: NS_E_WMPCORE_FAILED_TO_BUILD_PLAYLIST Fix

The 30-second fix: Rename the current database

What's actually happening here is that Windows Media Player builds playlists from a local database (a set of .wmdb files). If something corrupts a file—a crash, a bad media file, or a Windows update that didn't clean up properly—the player can't parse it anymore. The error 0XC00D109E is the player saying "I can't read my own notes."

The simplest thing to try is forcing the player to rebuild those files from scratch. It'll re-scan your library folders, so you won't lose your actual media.

1. Close Windows Media Player completely. Check Task Manager to make sure it's not running in the background—sometimes it hangs and eats CPU.
2. Press Win + R, type %LOCALAPPDATA%\Microsoft\Media Player, and hit Enter.
3. In that folder, you'll see a bunch of .wmdb files. Delete them all. Don't worry—they're just cached data. The player will regenerate them next time you open it.
4. Launch Windows Media Player. It'll show an empty library briefly, then start scanning your default media folders. Wait 30 seconds to a minute for it to finish.

If the error disappears, you're done. You just cleaned a corrupt database.

The 5-minute fix: Reset the library and clear cache

Didn't work? The problem might go deeper—maybe the database files are locked by a stuck process, or the corruption spread to the Windows Media Player Network Sharing Service database too. Let's kill everything properly.

1. Open an administrative Command Prompt or PowerShell (right-click Start, choose Windows Terminal (Admin)).
2. Run these two commands to stop the services that lock the database:
   

   net stop WMPNetworkSvc
   net stop wuauserv

   The first is the media sharing service. The second stops Windows Update because it sometimes interacts with WMP's database.
3. Now delete the database files we talked about, and clear the library cache. Run:
   

   del /q %LOCALAPPDATA%\Microsoft\Media Player\*.wmdb
   del /q %LOCALAPPDATA%\Microsoft\Media Player\*.jpg
   del /q %LOCALAPPDATA%\Microsoft\Media Player\*.png

   The image files are album art thumbnails—sometimes a corrupted thumbnail causes the build failure.
4. Restart the services:
   

   net start WMPNetworkSvc

   wuauserv will start on its own next time you check for updates.
5. Open Windows Media Player. If it asks you to set up the library again, say yes and point it to your music/video folders.

The reason step 3 works is that .jpg and .png files in that folder aren't your originals—they're cached renditions. A thumbnail from a corrupt media file can trigger the build failure on scan.

The 15+ minute fix: Nuke the whole library from the registry

Still seeing the error? This is the big hammer. The database files we deleted are regenerated from a registry key that stores the library settings. If that registry entry is corrupt or points to a dead drive, the player will keep rebuilding the same broken database.

1. Back up your registry first — export the key before touching it. Open Regedit, go to:
   HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer\Player\Settings
   Right-click Settings and choose Export. Save the .reg file somewhere safe.
2. In that same key, look for a value named DatabaseVersion or MediaLibraryVersion. Delete it. Also delete any value named LastLibraryRefresh or LibraryRefreshState.
3. Now go to this key and delete the entire MediaPlayer key (yes, the whole thing):
   HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer
   Wait—don't do that if you have custom playlists you haven't exported. The registry stores your custom playlists. If you need them, export the playlists from WMP's library first (File > Export Playlist to .wpl).
4. Delete the %LOCALAPPDATA%\Microsoft\Media Player folder entirely—not just the files, the whole folder.
5. Reboot your machine. This clears any lingering handles.
6. Open Windows Media Player. It'll start as if it's the first time—no library, no playlists. Re-add your media folders. This forces a clean rebuild of the database from the folder scans.

What's happening under the hood: The registry key holds the library's version number and scan state. If it's corrupted, the player thinks it has a valid database but can't actually read it. Deleting the key and folder forces a fresh start.

When to give up and use something else

If you've done the 15-minute fix and it's still broken, the problem is probably a corrupt media file in your library that crashes the database build every time it's scanned. The real fix here isn't more registry surgery—it's finding that file. Try this:

• Temporarily move half your music/video folders out of WMP's monitored folders. Reopen WMP. If the error goes away, the bad file is in the half you moved. Narrow it down by halving again.
• If you don't have time for that, just switch to VLC or MPC-HC. They don't use this fragile database system. Sometimes the smartest fix is changing tools.

Most people hit this error after a Windows update or a drive letter change. The first two fixes resolve it 95% of the time. Don't waste an hour on it.