Consider the following scenario:
You change the distinguished name for a user who has many direct reports in the user profile in Microsoft SharePoint Server 2010.
You try to perform a full synchronization against the Active Directory Domain Services (AD DS).
In this scenario, the user profiles of the direct reports cannot be synchronized successfully. Additionally, you receive the following error message:
Ambiguous attribute flow from multi-value to single valued attribute.
To resolve this issue, apply this following hotfix package:
2459257 Description of the SharePoint Server 2010 Cumulative Update Server Hotfix Package (MOSS server-package): December 31, 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.