How to Fix MW3 Not Launching on Steam

Use this guide to fix Modern Warfare 3 not launching on Steam.

by Christian Bognar
Captain Price kneeling in a field with the "Call of Duty MW3" logo in the bottom left corner
Image: Activision

Games on Steam have been known to launch with issues here and there, and Modern Warfare 3 is the latest one having problems. If you encounter an error where your MW3 won’t launch on Steam, read this guide for possible fixes.

Modern Warfare 3 Not Launching on Steam Solution

Below you will find four possible solutions to Modern Warfare 3 not launching on Steam. Start with the first one, as it is the most likely solution, and work your way down if the problem persists.

Fix #1 – Run MW3 as Administrator

The most common solution to MW3 not launching on Steam is that the player isn’t running the game as an administrator. To run Modern Warfare 3 as an admin, right-click the Steam or MW3 shortcut icon on your PC and then select “Run as Administrator.” This should fix the error. Move on to method two if your MW3 is still not working.

Fix #2 – Scan and Fix Game Files

For many PC games that refuse to launch on Steam, the problem boils down to scanning and fixing the game files. To scan and fix files, head into the Steam Library and right-click on Modern Warfare 3. Next, click on Properties and then the option “verify file integrity.” Doing so will allow your system to review all of Modern Warfare 3’s files and replace the damaged ones, fixing the launching problems.

Related: MW3 Season 1: Release Date, Battle Pass, and Early Patch Notes

Fix #3 – Update GPU Drivers

Often, PC players forget to update GPU Drivers, which can lead to game issues. Updating the Graphics Drivers is a must, and you can do so by downloading the AMD or Nvidia app. Just make sure you download the proper one that matches your graphics card. You can also update drivers from the official website for your card, although it’s easier to have the app ready for any future problems.

Fix #4 – Uninstall and Re-install MW3 and Steam

If none of those fixes worked for you, your next best bet is to uninstall and then re-install both Steam and Modern Warfare 3. This should be a last-case scenario considering how large Call of Duty MW3 is, and the time to download can take hours, but it could be worth it as it most likely will fix the not launching error.

If your Modern Warfare 3 game continues not working on your Steam after trying everything in this guide, it may be time to contact Steam or Activision customer support teams.

- This article was updated on November 11th, 2023

About The Author

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Christian has been a writer of Attack of the Fanboy for over a year and has covered Shadows of Rose, Lords of the Fallen, Remnant 2, Lies of P, and more; his favorite genre is Survival Horror. He has a business degree but felt the need to take his love for video games to the gaming community. Outside of writing, you can find him listening to all types of podcasts, especially Always Sunny Podcast and Morbid True Crime.