Since Sept. 27, the following event has been logged once an hour in the Microsoft Azure AD Connect Agent Updater Admin log in Event Viewer (Applications and Services Logs > Microsoft > AzureADConnect > AgentUpdater > Admin):
Log Name: Microsoft-AzureADConnect-AgentUpdater/Admin
Date: 2019-09-27 12:52:03 PM
Event ID: 32012
Task Category: None
The Microsoft Azure AD Connect Agent Updater service failed to check for updates.
Additional details: 'The underlying connection was closed: An unexpected error occurred on a send.'.
It looks like Azure AD Connect may have auto-upgraded on Sept. 26 to version 184.108.40.206. Is this a known issue?