Fix NS_E_WMP_PROXY_NOT_FOUND 0XC00D11C4 in Windows Media Player

Windows Media Player can't find the proxy server when streaming. This usually happens after a network change or a misconfigured proxy setting. Here's the fix.

You're trying to stream a URL in Windows Media Player — maybe an internet radio station or a corporate training video — and instead of playing, you get hit with the error: NS_E_WMP_PROXY_NOT_FOUND (0XC00D11C4). The exact message reads: "Windows Media Player cannot play the file because the network proxy server cannot be found."

I see this most often when someone switches from a corporate network (where a proxy is required) to a home network (where there isn't one), or vice versa. It also pops up when Internet Explorer's proxy settings get corrupted or manually changed. The root cause? WMP doesn't use its own proxy configuration — it inherits it from Internet Explorer's connection settings. If IE can't find or resolve the proxy server, WMP gives up and throws this error.

Fix It in 3 Steps

Don't bother reinstalling WMP or running a system file checker — that's wasted time. The fix is in the proxy settings. Here's the process I've used a hundred times.

Open Internet Explorer's proxy settings. Yes, even if you don't use IE anymore. Press Win + R, type inetcpl.cpl, and hit Enter. Go to the Connections tab, then click LAN settings.
Set the proxy correctly. If you're on a network that doesn't use a proxy, just uncheck "Use a proxy server for your LAN". If you do need a proxy (like at work), check that the address and port are correct. Common ports: 8080, 3128, or 80. Ask your network admin if you're unsure.
Override WMP's cached proxy. Open WMP, go to Tools > Options > Network. Under Streaming proxy settings, select HTTP and click Configure. Set it to "Use proxy settings of the Web browser". Also check MMS and RTSP — set those to "Use browser settings" too. Click OK twice.

What If It Still Fails?

Sometimes the fix doesn't stick. Here's what else to check:

Run as admin. WMP might not have permission to read the proxy settings. Right-click WMP and select Run as administrator — then try the stream again.
Clear IE proxy cache. Open a Command Prompt as admin and run: netsh winhttp reset proxy. This clears WinHTTP's proxy cache, which WMP also relies on.
Check for group policy. Corp machines often have locked proxy settings via Group Policy. Run gpresult /h gp.html in a command prompt, open the HTML file, and look under Administrative Templates for any proxy-related policies. If they're enforced, you'll need IT to update them.
Test with a local file. Try playing an MP3 from your hard drive. If that works but streaming doesn't, the problem is definitely proxy-related. If local files also fail, you've got a bigger issue — check Windows Audio service and codecs.

One last thing: if you recently installed any VPN software or security suite (looking at you, Norton and Kaspersky), they sometimes hijack proxy settings. Temporarily disable them to test. I can't tell you how many times that's been the hidden culprit.