The error message "uplay-ach-earnachievement could not be located" typically occurs when there's a problem with the Uplay platform or the game you're trying to play. This issue can prevent you from accessing achievements, rewards, or even playing the game.

Some users have resolved this by manually replacing the uplay_r1.dll and uplay_r1_loader.dll files in the game's main directory with updated versions sourced from a working Ubisoft Connect installation.

The error is a file integrity issue. In 90% of cases, simply using the "Verify Files" function within the Ubisoft Connect launcher will resolve the problem immediately.