MSDN Blogs: KB: Microsoft Azure AD Management Agent hangs during Full Import or Delta Import

When you run a Full Import or a Delta Import on the Microsoft Azure Active Directory (Azure AD) Connector, one of the following actions occur: 1. The following error is logged in the Application Event Log: FIMSynchronizationService Event 6801 The extensible extension returned an unsupported error. The stack trace is: “System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary. at System.Collections.Generic.Dictionary`2.get_Item(TKey key) at System.Collections...(read more)