Fix NS_E_SESSION_NOT_FOUND (0XC00D2EF3) on Windows
This Windows Media Player error means the streaming session got lost. Quickest fix: restart the player or app. If that fails, reset network settings or flush the DNS cache.
30-Second Fix: Restart the Player and Check the Source
I've seen this error pop up when you're streaming a video or audio file and the server hiccups. The fastest thing to try: close Windows Media Player completely (right-click its taskbar icon and pick 'Close window'), then reopen it. Also double-check the URL or file path you're trying to play. If it's a broken link, you'll keep seeing that error.
Still getting 0XC00D2EF3? Move on to the next step.
5-Minute Fix: Clear the DNS Cache and Reset Network Stack
This error often means your PC lost track of the network session. A quick DNS flush usually fixes it. Open Command Prompt as administrator (search for 'cmd', right-click, 'Run as administrator'). Then run these commands one by one:
ipconfig /flushdns
netsh winsock reset
netsh int ip resetAfter each command, you'll get a confirmation message. Restart your computer. Now try the media again. This clears out any stale network data that might be confusing the player.
If you're using a VPN or proxy, turn that off temporarily. Some VPNs interfere with streaming sessions and trigger this exact error.
15+ Minute Fix: Reset Windows Media Player Settings and Check Firewall
When the simple stuff doesn't work, it's time to dig deeper. First, reset Windows Media Player's library. Close the player, then press Windows + R, type regedit, and hit Enter. Navigate to:
HKEY_CURRENT_USER\Software\Microsoft\MediaPlayerRight-click the MediaPlayer key and choose 'Export' to back it up. Then, delete the entire MediaPlayer key. Restart Windows Media Player—it will rebuild its database from scratch. This nukes any corrupted session data stored locally.
Next, check your firewall. Windows Defender Firewall can block streaming sessions if it misidentifies the traffic. Go to Control Panel > Windows Defender Firewall > Allow an app or feature through Windows Defender Firewall. Make sure 'Windows Media Player' is checked for both Private and Public networks. If it's not there, click 'Change settings' then 'Allow another app' and browse to C:\Program Files\Windows Media Player\wmplayer.exe.
If you're still stuck after that, try disabling IPv6 temporarily. It's not common, but I've seen IPv6 mismatch cause session errors. Go to Network and Sharing Center > Change adapter settings, right-click your active connection, choose 'Properties', and uncheck 'Internet Protocol Version 6 (TCP/IPv6)'. Reboot and test.
Last resort: run the Windows Media Player troubleshooter built into Windows 10 and 11. Search for 'Troubleshoot settings', click 'Additional troubleshooters', find 'Windows Media Player', and run it. It'll scan for common issues like missing codecs or corrupted files.
Pro tip: If you're streaming from a local network share, make sure the device hosting the media is on and the folder is shared with read permissions. Network discovery turned off can also cause this.
That's the full breakdown. Start with the 30-second fix, work your way down. Most people stop after the DNS flush. If you're reading this, you probably already tried that, so jump to the registry reset. Good luck.
Was this solution helpful?