NS_E_BKGDOWNLOAD_INVALIDJOBSIGNATURE (0XC00D1261) on Windows

Corrupt job file in Media Player's background download cache

This is the #1 cause. Had a client last month whose entire print queue died because of this — well, not the print queue, but the Media Player background download service got stuck on a bad job file. Windows Media Player uses a background downloader to fetch metadata, album art, or update licenses. When that job file's signature doesn't match what the service expects, you get 0XC00D1261.

The fix: kill the hanging job file. Open File Explorer, paste this into the address bar:

%LOCALAPPDATA%\Microsoft\Media Player

Look for any files with weird names like ~WMP*.tmp or WMP*.job. Delete everything inside that folder. Don't delete the folder itself. If Windows says a file is in use, open Task Manager, kill wmplayer.exe and wmpnetwk.exe, then delete. Restart Media Player — it rebuilds the cache fresh. Error gone.

If you're lazy like me, run this in an admin Command Prompt:

del /q /s "%LOCALAPPDATA%\Microsoft\Media Player\*.*"

Then restart. That's it. 90% of the time this is the whole story.

Corrupt Media Player database

Sometimes the job file isn't the problem — the database that tracks all your downloads is corrupted. This happens when you force-quit Media Player during a metadata download, or after a Windows update that didn't shut down the service cleanly.

To reset the database, close Media Player completely. Then delete the database files:

1. Close everything Media Player related.
2. Open %LOCALAPPDATA%\Microsoft\Media Player again.
3. Delete these files: wmdb.db, wmdb.bak, and wmdb.log if present.
4. Also delete any *.sdf files (those are SQL Server Compact databases that store playback history).

Start Media Player — it will rebuild the database from scratch. You'll lose your play counts and ratings, but the error goes away. Worth it.

One time a client had a corrupted wmdb.db that was 2GB — caused this error every time they tried to download album art. Clearing that fixed it instantly.

Corrupted Windows Media Player Network Sharing Service

Less common, but if you've tried both fixes above and still get 0XC00D1261, the background download service itself might be busted. The service WMPNetworkSvc handles background jobs. If its internal state is corrupted, it can't validate new job signatures.

Here's the fix:

1. Press Win+R, type services.msc, hit Enter.
2. Find Windows Media Player Network Sharing Service.
3. Right-click, choose Stop.
4. Open Command Prompt as admin, run:

sc delete WMPNetworkSvc

Then restart Windows. Media Player will recreate the service on next launch. This is nuclear — it also nukes any network sharing settings you had. But it's a clean slate.

I've only needed this twice in the last five years, but both times it was the only thing that worked.

Quick-reference summary

Start with job file deletion. That's the fix in 9 out of 10 cases. If you're still stuck after that, move to the database, then the service. Don't bother reinstalling Media Player — it's baked into Windows and can't be removed.