NS_E_OPEN_FILE_LIMIT (0XC00D0031): Fix for Too Many Open Files

Quick answer for advanced users

Kill idle processes to free file handles, or increase the IrpStackSize registry key under HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters to 24 or higher. Reboot after.

Why this happens

I know this error is infuriating — you're just trying to play a video or stream from a network share, and suddenly Windows Media Player throws NS_E_OPEN_FILE_LIMIT (0XC00D0031). It translates to "The client cannot have any more files open simultaneously." That's not a lie — it's hitting a real wall.

Here's the deal: Windows limits how many file handles a single process can open. By default, the server-side limit (for network shares) is 16384 handles per computer, but the client-side limit is lower. If you've got Chrome with 50 tabs, a file explorer with 10 folders, and a bunch of background apps all holding files open, you'll hit this limit fast. I've seen it happen when someone streams a 4K video from a NAS while running a backup tool that also opens hundreds of files. The system just says "no more."

Fix steps

1. Close unnecessary programs — especially browsers, file explorers, and media players. This frees up handles instantly. Try playing the file again.
2. Check handle count — download Sysinternals Process Explorer (free from Microsoft). Run it, press Ctrl+H, then sort by "Handles." Look for processes with >10,000 handles. Chrome and Firefox are common culprits. Kill or restart them.
3. Increase the IrpStackSize — this is the real fix for network shares:
   1. Open Regedit as Administrator.
   2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
   3. Create a DWORD (32-bit) named IrpStackSize if it doesn't exist.
   4. Set its value to 24 (decimal). This gives the server more I/O request packet stack space.
   5. Reboot the machine.
4. Increase MaxMpxCt — if you're on a network share, also check this key under the same path: MaxMpxCt. Set it to 2048 (decimal) to allow more simultaneous client requests.
5. Disable Windows Media Player network sharing — if you don't need streaming from other devices, open WMP, go to Tools > Options > Library, and uncheck "Share my media." This reduces handles.

Alternative fixes if the main one fails

• Use a different player — VLC Media Player handles file limits more gracefully. It won't fix the underlying issue, but it might bypass the error for that file.
• Restart the Server service — run net stop lanmanserver && net start lanmanserver in an elevated command prompt. This flushes open handles on the server side.
• Check for malware — sometimes crypto-miners or other junk hold thousands of handles. Run Malwarebytes or Windows Defender Offline scan.
• Increase system-wide handle limit — this is rare, but you can edit HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PoolUsageMaximum to a higher value (like 64). Reboot required.

Prevention tip

Stop letting apps run wild. Use a tool like Handle (from Sysinternals) to periodically check which processes are hogging resources. Set a monthly reminder to reboot your PC — it clears stale handles. Also, ditch Chrome if you're a tab hoarder like me. Firefox with a tab suspender uses way fewer handles. Your video player will thank you.