The error " Assetto Corsa is obsolete (v1.16.3 is required)" is a common false-positive notification typically encountered by users of the Content Manager (CM) Custom Shaders Patch (CSP)
Even if you think you’re up to date, do this:
Wait for Steam to scan. If it finds missing files, it will redownload the necessary data to bring you to v1.16.3. Phase 2: Update Content Manager (CM)
The error occurs because the game performs a file integrity check (checksum) when connecting to a server. If even a single file—a car texture, a shader, a sound effect—does not match the server’s expected "vanilla" v1.16.3 standard, the server rejects you.
: While newer sims might have more complex aero models, AC’s tire feel and VR implementation remain top-tier for mid-range PC setups.
To understand the fix, you must understand the architecture of modern Assetto Corsa .