Today I went to upgrade the Azure AD Connect for a small client. This environment is quite small and the Azure AD Connect is installed on a domain controller.
I went through the motions but received an error- "Group with name ADSyncAdmins was not found in the machine context". This is a domain controller so there are no local users and groups. I reviewed the Event Logs and found several groups had the same error.
After some contemplating, I decided to create the groups in Active Directory (Domain security groups). The following groups were created-
I did not populate the groups and re-ran the wizard which completed successfully.