Fix NS_E_WMP_PATH_ALREADY_IN_LIBRARY Error

This pops up when Windows Media Player spots a duplicate file path in its library. It's a library sync glitch, not a real problem with your media files.

You're playing music in Windows Media Player, and suddenly it throws this error: "This file path is already in the library." The exact code is 0XC00D0FBA. I've seen this most often when you drag a music folder into WMP's library, or when WMP tries to automatically scan a network share that already has its content added. Happens a lot with NAS drives or shared folders on a home server.

Why This Happens

WMP keeps a database (the library) that tracks where your media files live. When you add a folder, it scans the folder and adds each file's path to that database. The error means WMP thinks the exact same file path is already there — maybe from a previous scan, or a corrupted index entry. It's not a file problem; it's a library database hiccup. The real fix is to force WMP to rebuild its library, clearing out stale entries.

Skip any suggestion to run a registry cleaner or reinstall WMP. That's overkill. The library is just a set of files in your user folder.

How to Fix It

Here's the step-by-step that's worked for every client I've had with this issue:

Close Windows Media Player completely. Make sure it's not running in the background — check Task Manager if you're unsure.
Open File Explorer and paste this into the address bar: %userprofile%\AppData\Local\Microsoft\Media Player
Delete all files and folders inside that Media Player folder. You might see files like CurrentDatabase_372.wmdb or folders like Sync. Select them all and hit Delete. Windows might say some files are in use — that's fine, just skip those (they'll be recreated).
Restart Windows Media Player. It will automatically rebuild the library database from scratch. This takes a minute or two, especially if you have a big collection.
Re-add your media folders. Go to Organize > Manage Libraries > Music (or Videos, Pictures), and add the folders you want. Don't worry about duplicates now — the clean database handles them correctly.

If It Still Fails

If the error comes back after rebuilding, the issue is likely with a specific file or folder path that's corrupted or has weird permissions. Had a client last month whose entire print queue died because of this — turned out one MP3 file had a read-only attribute set on the folder itself. Check the folder you're trying to add: right-click it, go to Properties, and make sure "Read-only" is unchecked. Also, if it's on a network drive, map the drive with a letter (like Z:) instead of using a UNC path (\server\share). WMP handles drive letters better.

If you're still stuck, try running WMP as administrator once — just right-click its shortcut and choose "Run as administrator". That clears any permission locks on the library files. After that, it should work normally.

Bottom line: this error is a library database glitch, not a file corruption. Deleting the database files is the quickest fix. Takes 5 minutes.