Final Update: Thursday, 23 September 2021 18:52 UTC
We've confirmed that all systems are back to normal with no customer impact as of 09/23, 16:15 UTC. Our logs show the incident started on 09/23, 15:30 UTC and during this timeline customers using Activity Log Alerts may have received errors when accessing Azure Activity Log Alert Rules.
Preliminary Root Cause: The failure was due to unavailability of dependent resource.
Incident Timeline: 09/23, 15:30:MM UTC through 09/23, 16:15 UTC
We understand that customers rely on Activity Log Alerts as a critical service and apologize for any impact this incident caused.