Error carrying out the user_protectedfromaccidentaldeletion_Get operation

Hi,

I've encountered the following error when running Active Directory Initial Synchronization.

[System.Exception] Error carrying out the user_protectedfromaccidentaldeletion_Get operation on object CN=ASPNET,CN=Users,DC="blank",DC=lan (Error: [System.Reflection.TargetInvocationException] Exception has been thrown by the target of an invocation.
[System.NullReferenceException] Object reference not set to an instance of an object.).

The synchronization was running just fine until now.

Any suggestions on what might be causing this error?

Temporary fix

I excluded all users that Synchronization Editor didn't have permission to perform user_protectedfromaccidentaldeletion_Get operation, but this is not the solution. In some cases we do not have permission to read this attribute and this will always cause synchronization to fail. Is there a workaround?

Thanks