Move your steamapps folder back into the new Steam directory to avoid re-downloading your games. Critical Safety Warning
If you've tried all the above methods with no success, a full reinstall is your final, fail-safe option.
If the error persists across multiple games, your core Steam installation might be compromised. Close Steam completely.
Ensure you download the correct 64-bit version and place it directly into the Black Ops 3 installation folder (usually found in steamapps/common/Call of Duty Black Ops III ). Move your steamapps folder back into the new
To prevent it from happening again, add your Black Ops 3 installation folder to your Exclusions or whitelist. Method 3: Install Visual C++ Redistributables
If your operating system registry or core system file paths are misconfigured, games will fail to read locally stored DLL components.
Click , select Folder , and choose your main Call of Duty Black Ops III directory to prevent future deletions. Close Steam completely
Navigate to the Installed Files tab (formerly "Local Files").
Before trying any other methods, check your antivirus software's quarantine or protection history. If it's been accidentally flagged, you can often simply restore it and add an exception to prevent future issues.
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Below are the verified, step-by-step methods to resolve this issue and get your game running again. Method 1: Restore the File from Antivirus Quarantine
The "steam_api64.dll missing" error in Call of Duty: Black Ops 3 typically occurs because your antivirus software has mistakenly quarantined or deleted the file, or the file has become corrupted. This critical Dynamic Link Library (DLL) component allows the game to communicate with Steam servers for authentication and achievements. Method 3: Install Visual C++ Redistributables If your
If the file was permanently deleted, Steam can automatically redownload the correct version. Open your .