How to Fix Delta Force “Anti-Cheat Not Installed” on PC?

The Anti-Cheat Not Installed message stops Delta Force before its game window opens. Steam can still show the game as fully downloaded because the failure occurs in ACE, a separate startup component that must load first.

Delta Force uses Anti-Cheat Expert (ACE) to complete this check. The message appears when its files are missing, its installer did not register them, or Windows left its service disabled.

Graphics settings do not take effect this early in startup.

The quickest clue is what remains on the PC: the ACE installer, an ACE service, or a security-history entry. Use the table below to begin with the repair that matches what you find.

1. Restart Windows, Then Verify Delta Force in Steam

During an update, Steam can finish the main download while an ACE file is still locked or incomplete. Restarting releases the old file; verification then restores anything missing or damaged. Begin here when the error followed an update, interrupted download, or first installation.

Verification is not needed when Steam already completed it after the latest restart; in that case, proceed to the bundled installer below.

1. Close Delta Force and Steam, then restart Windows once.
2. Open Steam > Library, right-click Delta Force, and select Properties.
3. Open Installed Files and select Verify integrity of game files.

   

4. Wait for Steam to finish, then launch the game once. Appuals’ game-file verification guide shows the equivalent path in other launchers.

If the game now opens, ACE was incomplete. If Anti-Cheat Not Installed returns, continue to Method 2 and repair the bundled installer.

2. Run the Bundled ACE Installer, Then Rebuild Its Folder if Necessary

Delta Force includes its own ACE setup program. Use it after verification when the files are present but Windows still does not recognize ACE as installed. Running this bundled setup, or letting it remove and redeploy ACE, has repeatedly restored launch for affected players.

The setup rebuilds ACE’s Windows registration instead of replacing unrelated game files. The folder reset is not needed when the bundled installer completes successfully.

1. In Steam, right-click Delta Force and select Manage > Browse local files.
2. Open Game\DeltaForce\Binaries\Win64\AntiCheatExpert.
3. Right-click ACE-Setup64.exe and select Run as administrator. If setup offers only Uninstall, confirm it while the game is closed, restart Windows, and launch Delta Force so the official package can be installed again.
4. If the setup file is missing or the repair still fails, close Steam and rename the AntiCheatExpert folder to AntiCheatExpert.old. Renaming keeps a recoverable copy while removing the broken folder from the active path.

   

5. Verify the game files again so Steam downloads a fresh ACE folder.

   

If the game opens, ACE was missing or registered incorrectly. If a fresh folder exists but the message remains, continue to Method 3 and inspect the ACE service.

3. Restore an ACE Service Only if Windows Has Disabled It

ACE can exist on disk while its Windows service is disabled. Reports after Delta Force updates show this state producing the same missing anti-cheat behavior. Service names can vary by build, so change only an entry that clearly contains AntiCheatExpert or ACE.

1. Press Windows + R, type services.msc, and press Enter.
2. Look for AntiCheatExpert Service, AntiCheatExpert Protection, or another ACE entry.
3. If its Startup type is Disabled, open Properties, change it to Manual, and select Apply.

   

4. Leave an ACE service that is already Manual or Automatic unchanged. Restart Windows and test the game.

Do not change unrelated services or force every ACE entry to Automatic.

4. Close Software That Interferes with ACE’s Launch Check

ACE can stop its launch check when another program can alter, inspect, automate, capture, or remotely control the game. Closing that program prevents it from attaching before ACE finishes.

Delta Force’s official software list names debuggers, automation scripts, virtual machines, hardware macros, remote-control apps, and frame-capture tools.

Use this comparison only if ACE files and services are intact, especially when the error also names incompatible or risky software. Close the relevant program instead of weakening ACE.

1. Exit any debugger, automation script, virtual machine, remote desktop tool, frame-capture utility, or macro software that is open.
2. For one clean comparison, also exit monitoring or overlay tools such as MSI Afterburner and RivaTuner Statistics Server. These are not automatically malicious; the test only removes an extra launch-time hook.

   

3. In Steam > Delta Force > Properties > General, temporarily turn off Enable the Steam Overlay while in-game.

   

4. Launch Delta Force. If it opens, re-enable optional tools one at a time to identify the conflict.

If no obvious program is responsible, use Appuals’ clean-boot walkthrough for one controlled test. A clean boot is diagnostic; restore normal startup afterward.

5. Restore ACE Only When Security History Shows an Actual Block

Security software can quarantine an ACE DLL and leave the rest of the folder intact, making the installation appear complete when it is not. Check the history before adding exclusions or changing firewall rules.

Restoring the verified DLL rebuilds the component ACE is trying to load. Do not add an exclusion unless protection history identifies a file inside the official game folder.

1. Open Windows Security > Virus & threat protection > Protection history. Microsoft explains the available actions in its Protection History guide.

   

2. Check any third-party antivirus quarantine as well. Restore a file only when its original path is inside the official Delta Force AntiCheatExpert folder.
3. If the same verified ACE file is blocked again, add the official game folder to that antivirus’s exclusions, then verify the game files once more.
4. Check the firewall only after a blocked connection or ACE network error. Use Allow an app through Windows Defender Firewall for the official executable; do not open ports.

   

Microsoft’s firewall safety guidance explains why allowing a known app is safer than opening a port.

6. Reinstall Once, Then Send Delta Force Support the Useful Evidence

A full download is justified only after file repair, the bundled installer, the service check, and a clean launch have failed. Reinstalling earlier can recreate the same blocked ACE state without revealing its cause.

A reinstall is not needed when Windows Security is still quarantining ACE; the fresh copy will be removed again.

1. Uninstall Delta Force from Steam, restart Windows, and reinstall the game to a normal local library. Do not manually remove system drivers or services that merely contain ACE.

   

2. Launch once with overlays and conflicting tools still closed, and accept the Windows administrator prompt from the official installer.
3. If the error returns, open the official Delta Force support path and include the exact error, Steam version, Windows version, and a screenshot.
4. State whether ACE-Setup64.exe ran successfully, whether an ACE service exists and is disabled, and whether Protection History quarantined an ACE file.

   

If a clean install opens, the game-side ACE package was damaged. If it fails with the same message, stop repeating reinstalls; the installer, service, and security results above give support the evidence needed to isolate the remaining block.