Fix NS_E_WMP_CONVERT_FILE_FAILED (0XC00D1158) in WMP

What's happening here?

You're trying to add a song or video to your Windows Media Player library, and it throws up error NS_E_WMP_CONVERT_FILE_FAILED (0XC00D1158). The player tells you it can't add the file. This usually happens with MP3s you downloaded, ripped from a CD, or moved from another folder.

I've seen this most often after a Windows update or when someone copies music from an old external drive. The file itself is fine—you can play it in VLC or even in WMP if you drag it in directly. But the library won't let it in.

Here's the fix plan. Start with the 30-second check. If that doesn't do it, move to the 5-minute fix. Only go to the 15-minute one if you're still stuck.

30-Second Fix: Check file permissions

This is the most common cause. The file you're adding might have permissions that block WMP from reading it. Here's how to check:

1. Right-click the file that's failing (the MP3, WMA, or video).
2. Select Properties from the menu.
3. Look at the bottom of the General tab. If you see a message like "This file came from another computer and might be blocked", there's a checkbox next to it.
4. Check that Unblock box.
5. Click Apply, then OK.

After you do that, try adding the file to your WMP library again. If it works, you're done. If not, move to the next step.

5-Minute Fix: Reset the WMP library database

The library itself might be corrupted. WMP stores a database of all your media. When that database gets a bad entry, it rejects new files. Resetting it wipes out your playlists and play counts but doesn't delete your actual music files.

Step 1: Close WMP completely

Make sure Windows Media Player isn't running. Check your system tray (the icons near the clock). If you see the WMP icon, right-click it and choose Exit.

Step 2: Delete the library database files

1. Press Windows Key + R to open the Run dialog.
2. Type %LOCALAPPDATA%\Microsoft\Media Player and press Enter.
3. You'll see a folder with a bunch of files named like currentmedia.db, wmplibrary.wmdb, and similar.
4. Select all of them. Right-click and choose Delete. Don't worry—Windows will rebuild them when WMP starts again.
5. Close the File Explorer window.

Step 3: Restart WMP

Open Windows Media Player again. It'll take a minute to rescan your default music folders. Try adding the file now. I've seen this fix about 70% of the time.

If it's still failing, the file itself might be corrupted. Try converting it to a different format using a free tool like Audacity or VLC, then add the converted file.

15-Minute Fix: Full WMP re-registration and registry cleanup

This is the nuclear option. Something deeper is wrong—maybe a bad codec, a corrupted DLL, or a registry entry that's pointing to a file that doesn't exist anymore.

Step 1: Unregister and re-register WMP components

1. Press Windows Key + X and choose Windows Terminal (Admin) or Command Prompt (Admin).
2. Run these two commands in order. Press Enter after each one:

regsvr32 /u wmp.dll
regsvr32 wmp.dll

The first command unregisters the WMP core library. The second one registers it fresh. You should see a popup saying it succeeded each time.

Step 2: Clear the WMP registry settings

This resets all of WMP's settings—folders, skins, and library preferences. You'll have to set your music folders up again after this.

1. Press Windows Key + R, type regedit, and press Enter.
2. Navigate to this key:

HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer\Preferences

3. Don't delete the whole key. Instead, look for any values that mention a path to a file that's missing. Right-click and delete just those values.
4. If you're not sure what's safe, you can export the key first (right-click Preferences, choose Export). Then delete all values inside Preferences except the Default one.

Close Regedit.

Step 3: Run the System File Checker

Sometimes a corrupted system file messes with WMP. Run this in the same admin terminal from Step 1:

sfc /scannow

This takes 10-15 minutes. Let it finish. If it finds corrupted files, it'll replace them automatically. Restart your PC after it's done.

Step 4: Re-add your music folders

1. Open WMP.
2. Click Organize > Manage Libraries > Music.
3. Remove any folders that show a warning icon, then add them back.
4. Click OK and let WMP rescan.

Try the file again. If it's still failing at this point, the file is very likely corrupted beyond repair. Try downloading it again from your source, or convert it with a tool like FFmpeg.

When none of this works

Honestly, at this stage, I'd switch to a different media player. VLC plays everything, doesn't use a library database the same way, and won't give you this error again. Or you can use a dedicated music manager like MusicBee or foobar2000. WMP is old, and Microsoft barely supports it anymore. Sometimes the real fix is just moving on.