Sometimes, the error is not a user error. The Steam version, as of 2025, still ships with a known bug: the steam_api.dll included in the depot is sometimes version 1.0 while the executable expects version 1.2. This mismatch causes a false "missing file" error.
This process will not restore files deleted by antivirus if the antivirus is still running. Turn off real-time protection temporarily before verifying. prototype 2 missing files
The community fix (if official verification fails) is to download a clean, updated steam_api.dll from the Steamworks SDK redistributable, available via the "Steamworks Common Redistributables" tool in your Steam Library (under "Tools"). Sometimes, the error is not a user error
The most common cause of "missing files" is a corrupted installation. Steam may fail to download specific libraries required for the game to launch. Open your Steam Library . Right-click Prototype 2 and select Properties . Navigate to the Installed Files (or Local Files) tab. This process will not restore files deleted by