Modifying the game or attempting to play it offline without a proper connection can cause verification mismatches. If the DLL version does not align with the current executable update patch of Hitman: Absolution , initial handshakes fail. Safe and Effective Resolution Strategies
For the specifically, the Steam Verification method (Solution 3) is the absolute best route. steamapidll for hitman absolution professional edition best
The best and safest methods for restoring this file for your Professional Edition include: Modifying the game or attempting to play it