This error usually pops up in because of a minor version mismatch between your game files and what the Custom Shaders Patch (CSP) expects. Even though you likely have v1.16.4 (the latest Steam version), CM sometimes gets confused and thinks it's "obsolete" because it's looking for v1.16.3 .
The most effective way to bypass this message without reinstalling the entire game is to manually trick the software into seeing the required version number. This error usually pops up in because of
If the game runs but "Extra Quality" settings (like SSLR or High-res shadows) are broken: This error usually pops up in because of