How to fix
Modern Warfare “Error cause: 10. Error code: 2004”
on Windows

Hi. Today I tried to load into the Call of Duty Modern Warfare lobby, just as I usually do, and I received an error "A matchmaking lobby error has occurred. Error cause 10. Error code 2004." I've been waiting all day, and the result is always the same. Please advise if this can be fixed.

Call of Duty Modern Warfare is a massive franchise with a huge fan base, and its multiplayer mode is particularly popular. Millions of players worldwide compete against each other in fast-paced, high-stakes online matches.

However, some players have reported encountering an error that prevents them from playing multiplayer matches. The error message they receive reads, "A matchmaking lobby error has occurred. Error cause 10. Error code 2004."

This error code can be a frustrating issue for players who want to enjoy the game with their friends. The matchmaking lobby error occurs during online play and prevents players from joining multiplayer matches. "Error cause: 10. Error code: 2004" is a result of a server issue at Activision or internet connectivity problems. Additionally, firewall settings might block the connection between the game client and servers, triggering the error.

Players might wonder why they receive this error code, especially if they have stable internet connectivity and have not made any significant changes to their firewall settings.

Unfortunately, sometimes, these errors can be due to issues on the game's server side. This means the players' computer or console is working correctly, but the game's server is not responding correctly, leading to a matchmaking lobby error.

In the case of the latter, there are several things you can do to fix the "Error cause: 10. Error code: 2004" in Windows. We provide a step-by-step guide below, although you should check your system with a PC repair tool [d1], which can diagnose issues and fix them automatically for you.

Solution 1. Check servers

If you face login issues while playing Call of Duty, it is essential to begin the troubleshooting process by verifying the server's status. You can check the server status by visiting websites such as Down Detector or following the official Activision Twitter account that provides instant updates on server issues. In case the servers are offline, regrettably, there is nothing you can do from your end, and you need to wait for Activision to resolve the problem.

Solution 2. Run network troubleshooter

A network troubleshooter is a software tool or a set of built-in diagnostic tools in an operating system that helps users identify and resolve common network connectivity issues. Network troubleshooters typically run a series of automated tests to diagnose network problems such as slow connectivity, intermittent connection drops, DNS issues, and network adapter problems. 

• Right-click on Start and pick Settings.
• Go to Network & Internet section.
• On the right side, find the Advanced network settings section.
• Click Network troubleshooter and wait.
• The fixes should be automatically applied.

Solution 3. Reset your internet

There are several components you can reset, such as Winsock and DNS.

• Type cmd in Windows search.
• Right-click on the Command Prompt result and select Run as administrator.
• When User Account Contol shows up, click Yes.
• In the new window, copy and paste the following command links, pressing Enter each time:
  ipconfig /flushdns
  ipconfig /registerdns
  ipconfig /release
  ipconfig /renew
  netsh winsock reset
• Close Command Prompt and see if the issue is fixed.

Solution 4. Use an alternative DNS

The default DNS provided by an ISP can cause connectivity issues for users as it may not always be reliable and could result in slow website loading times or complete disconnection from the internet. Additionally, some ISPs may intentionally limit their DNS service's speed to control internet traffic. To avoid such issues, users can consider switching to a third-party DNS provider such as Google DNS.

• Right-click on Start and pick Network Connections.
• Under Advanced network settings, pick Change adapter options.
• In the Network Connection window, right-click on your main connection (for example, Ethernet) and pick Properties.
• Select Internet Protocol Version 4 (TCP/IPv4) and click Properties below.
• Click Use the following DNS server address and type the following into the fields:
  Preferred DNS server: 8.8.8.8
  Alternate DNS server: 8.8.8.9
• Press OK.