: Some antivirus programs (notably Windows Defender or Avast) may quarantine essential game files like steam_api.dll , causing the "Steam must be running" error. Add the game's installation folder (typically ...\Steam\steamapps\common\DmC Devil May Cry ) to your antivirus exception/whitelist. Advanced Solutions for Modern Systems
Data Execution Prevention (DEP) sometimes blocks the DRM handshake. Adding DmC as an exception forces Windows to trust the process. : Some antivirus programs (notably Windows Defender or
Do not just close Steam. Perform a full kill: Adding DmC as an exception forces Windows to
: Ensure both Steam and the game's executable have proper permissions. Right-click the shortcut and select "Run as administrator." Navigate to the game files (Right-click in Library > Properties > Local Files > Browse) and set DMC-DevilMayCry.exe to "Run as administrator" in the Compatibility tab. Verify Integrity of Game Files Right-click the shortcut and select "Run as administrator