Since this DLL is part of the Ubisoft API, an outdated launcher can cause connection failures. Download the latest version of Ubisoft Connect Install it over your current version.
Before attempting complex solutions, try these quick checks: far cry 3 error ubiorbitapi-r2-loader.dll is missing
If the error persists and online features are not required, a direct workaround exists for original disc or non-Steam versions : Since this DLL is part of the Ubisoft
Instead of a full reinstall, let your game launcher find what's missing. far cry 3 error ubiorbitapi-r2-loader.dll is missing