0XC00D1129

Fix 0xC00D1129 – Windows Media Player network error

Network & Connectivity Beginner 👁 0 views 📅 May 26, 2026

This error means Windows Media Player can't reach the streaming server due to a network or firewall block. Here's how to fix it.

When does this error actually happen?

You're watching a news clip, a radio stream, or maybe a live concert online. Everything's fine for a few seconds. Then Windows Media Player stops and throws up the message: "Windows Media Player has encountered an unknown network error. The exact error code is: 0XC00D1129."

This happens most often when you're trying to open a streaming URL (like an .asx or .mms link) from a website or an email. It's not a corrupted file or a missing codec – it's a network problem that stops WMP from talking to the streaming server.

What's actually going on under the hood?

The error code 0xC00D1129 maps to NS_E_WINSOCK_ERROR_STRING in the Windows SDK. Winsock is the part of Windows that handles network connections. When WMP tries to open a TCP or UDP connection to the streaming server, something along the way is blocking or breaking that conversation.

The usual suspects are:

  • Windows Firewall (or third-party antivirus firewall) blocking WMP from reaching the internet
  • A proxy server that's misconfigured or requires authentication WMP doesn't know about
  • Corrupted Winsock catalog – happens after some network software installs or uninstalls badly
  • The streaming server itself went offline, but that's less common

Step-by-step fix

Try these in order. Most people stop at step 2.

Step 1: Check if the stream URL actually works

Before you blame your computer, make sure the stream isn't dead. Open a browser and paste the URL you tried to play in WMP. If your browser can download a file or play it, the stream is alive. If you get a "page not found" or a blank screen, the link is broken – contact the site owner.

Expected outcome: A file download starts, or you see a small player in the browser. If not, skip the rest and report the broken link.

Step 2: Run the Windows Media Player network troubleshooter

Windows has a built-in tool for this. Here's how to get to it:

  1. Open Windows Media Player.
  2. Press Alt to show the menu bar if it's hidden.
  3. Click Help > Windows Media Player Network Troubleshooter.
  4. Follow the prompts. It will test your proxy settings and firewall rules.
  5. If it finds a problem, it will ask to fix it. Let it do that.

Expected outcome: The troubleshooter either says "no issues found" or reports a blocked port. If it fixed something, try your stream again.

Step 3: Manually configure WMP's proxy settings

If the troubleshooter didn't help, WMP's proxy setting might be wrong. Let's set it to use the same proxy as Internet Explorer (which is usually correct):

  1. Open Windows Media Player.
  2. Press Alt to see the menu bar, then click Tools > Options.
  3. Click the Network tab.
  4. Under Streaming proxy settings, you'll see a list of protocols (MMS, RTSP, HTTP, etc.). For each one, click it and then click Configure.
  5. In the dialog that opens, select Use proxy settings of the Web browser.
  6. Click OK. Do this for all four protocols.
  7. Click Apply and then OK.

Expected outcome: After clicking Apply, you'll be back in the Options window. Close it and try your stream again. If it still fails, move to step 4.

Step 4: Reset the Winsock catalog

This is the nuclear option for network corruption. It clears out all custom Winsock entries and resets everything to default. You'll need an admin account.

  1. Press the Windows key, type cmd, right-click on Command Prompt and choose Run as administrator.
  2. In the black window, type this command and press Enter: 
    netsh winsock reset
  3. You'll see a message like "Successfully reset the Winsock Catalog."
  4. Then type this second command and press Enter: 
    netsh int ip reset
  5. Restart your computer when prompted.

Expected outcome: After the restart, your network connections might be briefly slower while they renegotiate – that's normal. Try WMP again.

Step 5: Temporarily disable your firewall (for testing only)

This step is just to see if the firewall is the problem. Don't leave it off – that's dangerous.

  1. Open Windows Security (search for it in the Start menu).
  2. Click Firewall & network protection.
  3. Click on the network profile that says "(active)" – likely Domain network, Private network, or Public network.
  4. Turn off Microsoft Defender Firewall.
  5. Try playing your stream.
  6. If it works now, you know the firewall was blocking WMP. You can either add WMP to the allowed apps list (search for "Allow an app through firewall" in the Start menu) or keep reading for a better approach.
  7. Turn the firewall back on immediately after testing.

Expected outcome: If the stream plays with the firewall off, the fix is to add an exception. If it still fails, the problem isn't the firewall.

Still stuck? Here's what to check next

If you've done all five steps and it's still failing, the problem is almost certainly on the server side or with your internet connection. Try these quick checks:

  • Can you play any other online stream in WMP? Test with a known working one like https://icecast.texxradio.com:8000/stream.mp3. If that plays, the problem is with the specific URL.
  • Are you on a corporate or school network? Many block streaming protocols entirely. Talk to your IT department.
  • Do you have a VPN enabled? Try disconnecting – VPNs can interfere with streaming.
  • Try using a different media player. VLC Media Player handles these streams much better and will give you a clearer error message if it fails.

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