If you find steam_api64.dll inside, select it and click or Allow on Device . Restart your computer and try launching Mafia 3. Method 2: Reinstall or Verify Integrity of Game Files
The safest and most reliable way to recover a missing or corrupted steam_api64.dll file is to use the built-in repair tool inside the official Steam client. This will automatically identify missing data and re-download authentic copies straight from Valve's servers. Launch your . Navigate to your Library tab. steam api ext 64dll mafia 3 full
If you would like to look into deeper software configurations, tell me: What are you running? Is this error happening with other Steam games ? Are you running the Definitive Edition of Mafia 3? If you find steam_api64