If using the client, select the game > Properties > Verify files . This automatically replaces missing DLLs. Manual DLL Replacement (Caution) :
Incomplete updates to the Ubisoft Connect client or interrupted game downloads can lead to missing or damaged files.
: Improperly uninstalled software or system updates can break the registry entries required to locate these DLLs. How to Fix uplay_r1.dll and uplay_r1_loader.dll Issues 1. Restore from Antivirus Quarantine
To understand why these errors occur, one must first identify the role of each file: