If you have tried all of these and the issue persists, the problem may be specific to a corrupted Windows user account. Creating a new local user account on your PC and trying to run the game from there is a reliable final test.

Go through the usual steps: Restart your PC; make sure Steam is running and no other Steam game/application is open; verify game f... Reddit Fatal Error, can't launch Assetto Corsa / Content Manager The module was expected to contain an assembly manifest. File name: 'WindowsBase, Version=4.0.0.0, Culture=neutral, PublicKeyToken... Steam Community Fix Steam API Error | Simple Guide | Updated - YouTube May 2, 2022 —

Here’s what it means and how to fix it:

If a core file (like steam_api64.dll ) is missing or corrupted, the game simply won't launch.

: Ensure both Steam and Content Manager are set to the same level. Right-click each .exe , go to Properties > Compatibility , and either check or uncheck "Run this program as an administrator" for both. 2. Update Content Manager Game Starter Settings

Security software may mistake the API call as a threat and block the handshake between the game and Steam.