Open your launcher (Steam or Battle.net), go to MW3 settings, and select "Verify Integrity of Game Files."

Here is the comprehensive guide to fixing MW3 offline issues and getting the game running without a constant internet handshake. Understand the "Always-Online" Barrier

This grants access to the Campaign and Local Multiplayer (split-screen/bots). Step 2: The "Disc Version" Workaround (Consoles)

Ensure the Battle.net or Steam client itself isn't stuck in an update loop, as this prevents the "Offline Mode" of the launcher from working correctly. Step 4: The "Installation Check" Fix

It is important to manage expectations. Even with these fixes, certain features remain locked: