While doing a regular maintenance check on my customers servers, running Windows 2012 Essentials, when I came across a new event in the log.
I’ve previously wrote about changing the sync schedule on this server.
But today I noticed two event errors, ADSync event 6127 and 6127.

ADSync Event Warning 6126

The management agent "DOMAIN.com - AAD" completed run profile "Delta Import" with a delta import or delta synchronization step type. The rules configuration has changed since the last full import or full synchronization.
 
User Action
To ensure the updated rules are applied to all objects, a run with step type of full import and full synchronization should be completed.

ADSync Event Warning 6127

The management agent "DOMAIN.local" completed run profile "Delta Import" with a delta import or delta synchronization step type. The rules configuration has changed since the last full synchronization.
 
User Action
To ensure the updated rules are applied to all objects, a run with step type of full synchronization should be completed.

To fix this I did pretty much what the event tells us to do. I launched the Syncronization Service Manager
(C:\Program Files\Microsoft Azure AD Sync\UIShell\miisclient.exe), went to the Connectors-tab.

Next right-click on the “local connector” (type Active Directory Domain Services), and then Press Run.
First run a “Full Syncronization”, when it has completed make sure to run a Full Import aswell.

Then proceed to do the same for the “AAD connector” (type: Windows Azure Active Directory).

Now all should be synced successfully. Re-run the task which handles the synchronization job and all should be running fine!