For Steam users, Error Code 2 often stems from a miscommunication where Steam tries to launch the legacy launcher, but the system has a newer Ubisoft Connect client installed.
I can provide specific or file path corrections once I know your platform.
Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Ubisoft\Launcher .
Delete manual entries related to the launcher signature (avoid deleting unrelated game data).