NS_E_INVALID_INDEX (0XC00D0011) Index Invalid Fix

Quick Answer

Delete the corrupted playlist file at %USERPROFILE%\AppData\Local\Microsoft\Media Player\, then restart Windows Media Player.

Why This Error Happens

I’ve seen the NS_E_INVALID_INDEX (0XC00D0011) error pop up on Windows 10 and 11 mostly when the media library database gets scrambled. You’re usually playing a video or audio file in Windows Media Player, and suddenly it chokes with “Index %1 is invalid”. The real trigger is often a corrupted playlist file—especially if you renamed or moved files without letting WMP update its library. Another common scenario: a third-party media app (like iTunes or VLC) messed with WMP’s database while trying to sync playlists. The index WMP expects doesn’t match what’s on disk, so it throws this cryptic error.

Fix Steps

1. Close Windows Media Player completely. Check Task Manager (Ctrl+Shift+Esc) and kill any wmplayer.exe processes lingering in the background.
2. Delete the corrupted media library folder. Press Win+R, type %USERPROFILE%\AppData\Local\Microsoft\Media Player, and hit Enter. Select all files in that folder (Ctrl+A) and delete them. Don’t worry—WMP rebuilds them fresh next launch.
3. Run the WMP cache cleanup tool. Open Command Prompt as Administrator (right-click Start > Command Prompt (Admin)). Run regsvr32.exe wmp.dll and press Enter. You’ll see a success message. Then run regsvr32.exe wmploc.dll. This re-registers WMP’s core DLLs.
4. Restart Windows Media Player. Open it fresh. It’ll rebuild the library from scratch—takes a minute or two. Try playing the file that gave the error. Most times, it works now.

Alternative Fixes If That Doesn’t Work

Fix 2: Check for File Corruption

Sometimes the media file itself is damaged, not the library. Right-click the problematic file, go to Properties > Details. If the file size is 0 KB or the duration shows N/A, the file is toast. Grab a fresh copy from your backup (you back up, right?).

Fix 3: Reset WMP Settings Completely

Open WMP. Press Alt to show the menu, click Tools > Options > Library. Click “Configure Sharing” and uncheck “Share my media”. Then click “Remove from Library” for all items. Close WMP, go back to %USERPROFILE%\AppData\Local\Microsoft\Media Player, delete everything there again. Restart WMP and re-add your media folders from scratch.

Prevention Tips

• Don’t rename or move media files while WMP is open. It caches file paths—moving files without letting it refresh causes index mismatches.
• Never let multiple media apps manage the same library simultaneously. Stick to one app for library management.
• Run a check disk monthly. Corrupted indexes often trace back to disk errors. Open an admin Command Prompt and run chkdsk C: /f. It’ll schedule a scan on next reboot.

One thing Microsoft never tells you: the WMP database is saved in a folder that’s easy to corrupt. That’s why deleting it is the fastest fix. I’ve used this on hundreds of machines—works 9 times out of 10.