Windows 10/11 Installation – Arma 2: Operation Arrowhead

Steam's Arma 2: Operation Arrowhead setup on Windows 10/11 can be quirky/troublesome; here is a step-by-step how-to:

Installation

⚠

Run Steam as administrator.

ⓘ

If you do not own a certain DLC, just skip its related steps.

1. Install Arma 2
2. Run Arma 2
3. Close Arma 2
4. Install Arma 2: Operation Arrowhead
5. Run Arma 2: Operation Arrowhead

DLCs:

1. Run Arma 2: Army of the Czech Republic - it should start installing to Arma 2: Operation Arrowhead
2. Install Arma 2: British Armed Forces
3. Run Arma 2: British Armed Forces - it should start installing to Arma 2: Operation Arrowhead
4. Run Arma 2: Private Military Company - it should start installing to Arma 2: Operation Arrowhead

The game should now work with all DLCs without problems, unless Windows 11 is used... see below.

Fixes

"You were kicked off the game" Issues

• Go to Steam\steamapps\common\Arma2\Addons
• Delete:
  • corepatch_a2.pbo
  • corepatch_a2.pbo.bi.bisign
  • corepatch_a2.pbo.bi2.bisign
• Go to Steam\steamapps\common\Arma 2 Operation Arrowhead\Expansion\Addons
• Delete:
  • corepatch.pbo
  • corepatch.pbo.bi.bisign
  • corepatch.pbo.bi2.bisign
  • corepatch2.pbo
  • corepatch2.pbo.bi.bisign
  • corepatch2.pbo.bi2.bisign
• Verify both games's file integrity (see Steam's FAQ entry)

Freeze Issues

The game may freeze without apparent reason. If so, run it with the malloc startup parameter:

arma2oa.exe -malloc=system

Windows 11 Specifics

Windows 11 needs further steps to resolve BattlEye issues:

• Download arma2oa-BE_A2OA_v164_2024_Windows11_fix_v2.7z (install 7zip if you do not have already)
• Close the game if it is running
• Go to <A2OAInstallationDir>\BattlEye (C:\Program Files (x86)\Steam\steamapps\common\Arma 2 Operation Arrowhead\BattlEye with default Steam installation location)
• Run Uninstall_BattlEye.bat
• Once done, go up two level back to C:\Program Files (x86)\Steam\steamapps\common\ (or equivalent on your system)
• Open the archive with 7zip. Drop its ARMA 2 Operation Arrowhead directory to the common folder and replace all of the files. This means that the BattlEye directory and Arma2_OA_BE.exe should be placed inside the game folder, rather than the common folder
• Go to the BattlEye directory, install BattlEye
• Run the game

That's it, everything should work fine. Enjoy Arma 2: Operation Arrowhead!