We've confirmed that all systems are back to normal with no customer impact as of 12/1, 16:30 UTC. Our logs show the incident started on 12/1, 13:35 UTC and that during the 2 Hours & 55 minutes that it took to resolve the issue customers using Application Insights and/or Azure Log Analytics in West Europe may have experienced latency/failures when accessing application data and misfired/failed alerts for these resources.
Root Cause: The failure was due to a backend service that became unhealthy due to high CPU usage causing impact to these services.
Incident Timeline: 2 Hours & 55 minutes - 12/1, 13:35 UTC through 12/1, 16:30 UTC
We understand that customers rely on Azure Monitor as a critical service and apologize for any impact this incident caused.