What's actually happening here
Windows Media Player (WMP) reads playlists as a set of references. Each entry points to a media file. But some playlist formats—especially ASX and WPL—allow a secondary reference called an "alternate ref." That's a fallback URL if the primary one fails. The error NS_E_WMPCORE_MEDIA_ALTERNATE_REF_EMPTY means WMP found an empty alternate ref tag, and it doesn't know what to do with it. So it bails out and shows you that error code.
This usually happens after you've edited a playlist by hand, or a program like VLC or a download manager wrote a malformed file. Sometimes it's a corrupted cache entry that points to a removed playlist. The fix depends on where the bad reference lives.
Here's a troubleshooting flow. Start with the quick fix—if it doesn't work, move to the next.
Quick fix (30 seconds): Clear the WMP cache
WMP keeps a database of your media library, including playlist metadata. If that database has a stale or corrupted entry, it can trigger this error even when the actual playlist file is fine.
- Close Windows Media Player completely.
- Press
Win + R, typetemp, and hit Enter. Delete everything inside (or just the folders that start with "WMP"). - Also clear the library cache: In WMP, press
Ctrl + 3to switch to Library view. Now go to Organize → Manage libraries → Music (or whatever library holds the playlist). Remove the folder and re-add it.
What's the logic? WMP's library cache can hold a reference to a playlist that no longer exists or has been moved. By forcing a full rescan, you flush that bad entry. Try playing the file again. If the error persists, move on.
Moderate fix (5 minutes): Locate and edit the bad playlist
If the cache isn't the issue, the playlist itself has an empty <ref href=""> or <alternateRef href=""> tag. You need to find that file and fix it.
Step 1: Find the playlist file
Check the folder you were playing from. Look for files with these extensions:
.asx— the most common culprit.wpl.m3u— but note that m3u doesn't support alternate refs, so this error rarely comes from m3u
If the error appeared when you clicked a link on a web page, it's likely a temporary ASX file. WMP sometimes writes these to %TEMP%. Open the temp folder and sort by date—look for recent .asx files.
Step 2: Open and inspect the file
Right-click the file and choose Open with → Notepad. Look for lines like:
<REF HREF="http://example.com/file.wma" />
<AlternateRef HREF="" />
The empty HREF is the problem. You have two choices:
- Delete the entire alternateRef tag — usually safe because the primary ref works.
- Put a valid URL in there — only if you know a backup location.
Save the file and try playing it again. If the file is in a temp folder and you can't find it, skip ahead.
Advanced fix (15+ minutes): Reset Windows Media Player
If you've cleared the cache and fixed obvious playlist files, but the error still pops up, WMP's own settings may be corrupted. Resetting it is more aggressive—it'll wipe your library and saved playlists—but it's the final step before reinstalling.
Step 1: Close WMP and kill background processes
Open Task Manager (Ctrl + Shift + Esc), find any wmplayer.exe processes, right-click and End Task.
Step 2: Delete the registry keys
WMP stores its settings in the Windows registry. Deleting them forces WMP to recreate them fresh.
- Press
Win + R, typeregedit, hit Enter. - Navigate to
HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer. - Right-click the
MediaPlayerkey and select Export to back it up (just in case). - Now right-click and Delete the whole key.
Don't worry—Windows will rebuild it the next time WMP starts.
Step 3: Clear the DRM folder
This step is often overlooked. The DRM folder can hold licenses that reference media files. If a license is broken, it can cause weird playback errors.
Open Explorer and go to %PROGRAMDATA%\Microsoft\Windows\DRM. Delete all files inside. WMP will recreate them as needed. Note: If you have purchased content, you might need to re-acquire licenses.
Step 4: Restart and test
Open WMP, wait for the library to rebuild, then try the playlist again. If the error is still there, it's likely the playlist file itself is truly broken—re-create it from scratch in WMP (File → Create Playlist) instead of editing the old one.
Why your situation might be different
One edge case: if you're using Windows Media Center or an older version like WMP on Windows 7, the registry path is the same, but the cache location differs. For Windows 7, the temp folder is still %TEMP%, but the library database lives in %USERPROFILE%\AppData\Local\Microsoft\Media Player. You might need to delete the CurrentDatabase_*.edb files there to force a full rebuild—that's more thorough than the quick fix.
Another scenario: the error can appear when you're trying to play a network stream that uses multicast or has a rollover URL. In that case, the playlist isn't local at all—it's being streamed to you. The fix is to contact the stream provider, because you can't edit what you don't have.
Preventing this from recurring
The root cause is almost always a poorly written playlist generator. If you use a tool to create playlists, make sure it's up to date. Older versions of some download managers and media converters produce broken ASX files. Stick with trusted software.
Also, if you hand-edit playlists, always validate the XML structure. A single unclosed tag or an empty attribute can trigger this exact error. Use a text editor that highlights XML syntax—Notepad++ or VS Code work fine.
And one more thing: don't use Windows Media Player for anything but legacy content. It hasn't been updated since Windows 8, and it shows. For modern media, VLC or MPC-HC won't complain about these malformed playlists—they're more forgiving. But if you must use WMP, the steps above will get you running.