7 Ways to Fix Call of Duty Modern Warfare 3 Not Working (Starting) on a Windows PC

Call of Duty: Modern Warfare 3 is one of the most popular shoot ‘em ups for Windows some players can’t play because that game doesn’t work (start) on their PCs. One COD: Modern Warfare 3 player said on Reddit, “MW3 Steam won’t launch… I click launch and it tries to launch then just doesn’t and reverts back to the play button.” These are some ways to fix Call of Duty: Modern Warfare 3 not working on Windows PCs.

Verify the Modern Warfare 3 Files

First, start by verifying MW3’s files, which is one of the most straightforward potential fixes for Call of Duty: Modern Warfare 3 not working to apply. Both Battle.net and Steam have troubleshooting options you can select to repair corrupted game files. These Blizzard Battle.net and Steam support pages include instructions verifying games with those gaming clients.

Steam’s Verify integrity button

Disable Full-Screen Optimizations

Some MW3 players confirm disabling full-screen optimizations is a resolution that can fix Call of Duty: Modern Warfare 3 not working. This potential fix also has an additional step for erasing a Call of Duty folder after selecting to disable full-screen optimizations. You can disable full-screen optimizations and delete that COD folder like this.

1. Click the Explorer folder library taskbar button to open the Call of Duty HQ game installation directory for Modern Warfare 3. The default Steam folder path for this directory is Steam > steamapps > common > Call of Duty HQ.
2. Right-click the cod.exe game file to select its Properties option.
3. Select Compatibility and the Disable fullscreen optimizations box within that tab.
   
   

   The Disable fullscreen optimization checkbox

4. To set the selected option, click Apply.
5. Close the cod.exe Properties window.
6. Click the Documents folder on the left of Explorer.
7. Right-click the Call of Duty folder in the Documents directory to select Delete.

Some players also say they’ve fixed Call of Duty: Modern Warfare 3 not working by disabling the Run this program as administrator option for the game. This seems odd since the game will lose admin rights with that setting disabled, but it’s confirmed to work nonetheless. So, try unselecting Run this program as an administrator if it’s selected on the Compatibility tab.

Close Background Apps With Overlays

Third-party overlay incompatibilities can cause startup issues for COD: Modern Warfare 3. Apps like Discord, GeForce Experience, Steam, MSI Afterburner, Mumble, XFire, and RadeonPro have overlays. So, try closing all unnecessary background apps with overlay features as follows.

1. Click Start with your mouse’s right button to select Task Manager.
2. Select Processes to view background apps.
   
   

   The End task option

3. Right-click the processes for apps with overlay features and select End task to close them.

Some players will need to have Steam running to launch COD: Modern Warfare 3. Disable that overlay feature if you’re a Steam user. These are the steps for disabling Steam’s overlay.

1. Bring up the Steam window.
2. Click Steam > Settings to access options.
3. Select In Game to access that tab.
4. Disable the Enable the Steam Overlay while in-game setting by clicking the toggle switch for it.
   
   

   The Enable the Steam Overlay while-in game option

Start Steam or Battle.net With Administrator Rights

Starting Steam or Battle.net with admin rights is another resolution that’s fixed Call of Duty: Modern Warfare 3 not working for some players. Doing this will give the gaming client admin rights rather than the game. You can configure Steam or Battle.net to run with admin rights like this.

1. Right-click your Battle.net or Steam desktop shortcut to select Properties.
   Navigate to the Compatibility tab.
2. Select Run this program as an administrator within the tab.
   
   

   The Run this program as an administrator checkbox

3. Press Apply to set the option selected.
4. Select OK to close the Steam or Battle.net properties window.

Set High Performance for Modern Warfare 3

Windows has low (power saving) and high-performance graphics settings for software. These settings can be the difference between dedicated and integrated GPUs for PCs with dual graphics adapters. Modern Warfare 3 won’t start if set to run with incompatible Intel GPUs. This is how you can set high performance for COD: Modern Warfare 3.

1. Access the file finder tool with its Windows logo + S hotkey.
2. Type in a graphics settings keyword.
3. Select Graphics settings to view those options.
4. Click the Desktop app on the Choose an app to set the preference drop-down menu.
5. Press Browse and select the cod.exe file within the Call of Duty HQ folder.
   
   

   The Browse button in Graphics settings

6. Click the Add option.
7. Next, click Call of Duty and its Options button.
8. Select the High performance setting.
   
   

   The High performance radio button

9. Click the Don’t use optimizations for windowed games checkbox.
10. Press Save to set your selected options.

Uninstall REWASD

Uninstalling the REWASD program is another confirmed troubleshooting method for fixing Call of Duty: Modern Warfare 3 not working. REWASD is keyboard and controller remapping software Activision has banned for usage with Modern Warfare 3. This means REWASD cannot even be installed on your PC if you want to play MW3.

The Programs and Features Control Panel applet

You can uninstall REWASD via Programs or Features or with its uninstall wizard. This REWASD help page includes instructions for removing that program with its uninstall wizard. Alternatively, utilize a third-party uninstaller tool, such as IOBit Uninstaller, to thoroughly remove that software and erase its leftover registry items.

Reinstall COD: Modern Warfare 3

A few MW3 have said they’ve fixed Call of Duty: Modern Warfare 3 not working by reinstalling the game. However, select to reinstall the game on the same drive as your Battle.net or Steam software if it’s not already. This Battle.net page includes guidelines for reinstalling games with Blizzard’s gaming client. Steam users can reinstall MW3 like this.

1. Start your Steam gaming app.
2. Click Library to view installed games.
3. Right-click Call of Duty: Modern Warfare 3 to select Manage > Uninstall.
4. Click Uninstall on the prompt requesting confirmation.
   
   

   Steam’s Uninstall option

5. Reinstall MW3 by clicking the Install option for the game in the Library tab.

The troubleshooting methods above are player-confirmed ways to fix Call of Duty: Modern Warfare 3 not working. So, maybe one of those potential solutions will kick-start MW3 on your PC too. However, you can submit a help ticket for MW3 from the Activision Support site if more potential fixes are needed.