Internal error in COM access layer: number: 8007202F, description: A constraint violation occurred.

while AD synchronization we are getting below error like "

2134002] Error executing an adhoc projection!
[1777018] Error executing workflow (Provisioning) of synchronization project

Error executing projection step (user) of projection configuration (Provisioning (Provisioning)).

[1777219] Error executing projection step (user)!

[1777004] Method (Update object (Update)) could not be executed successfully.

A constraint violation occurred.

Object not committed successfully. Retrying using single property commit.
Property userPrincipalName should be set.
Internal error in COM access layer: number: 8007202F, description: A constraint violation occurred.

A constraint violation occurred. 

when we checked in AD we could see that all the attributes are set correctly.How can we check the  constrained limit of AD attributes. 

Please help me.