Error Cause 10 Error Code 2901 | Call of Duty: Modern Warfare 2

This error is specific to Call of Duty (Modern Warfare III, Black Ops 6, or Warzone). The full message usually reads: “Lobby not found. Check the code and try again. Error cause: 10. Error code: 2901.”

It means your game has lost its “handshake” connection with the Activision servers, often because the game was suspended (Quick Resume) or your internet connection flickered.

Here is how to fix it, ranked from easiest to most likely to work:

1. The “Quick Resume” Fix (Xbox / PC)

If you are on Xbox Series X|S or using the Xbox App on PC, this is the most common cause. The “Quick Resume” feature breaks the server connection.

• Action: Press the Xbox button, highlight the game, press Menu (Start), and select “Quit”.

• Relaunch: Start the game fresh. It forces a new login to the servers.

2. Restart Your Router

“Error Cause 10” is almost always a network timeout.

• Unplug your router for 30 seconds.

• Plug it back in and wait for the internet to fully reconnect before launching the game.

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3. Verify Game Files (PC Only)

If a restart doesn’t work, a file might be corrupted (common after an update).

• Steam: Right-click game > Properties > Installed Files > Verify integrity of game files.

• Battle.net: Click the Gear icon next to Play > Scan and Repair.

• Xbox App: Right-click the game in the sidebar > Manage > Files > Verify and Repair.

4. Sign Out & In (Xbox App Users)

If you are playing on PC Game Pass:

• Open the Xbox App on your PC.

• Sign out of your profile (top left corner).

• Sign back in and relaunch the game.