We've confirmed that all systems are back to normal with no further customer impact as of 10/21, 17:26 UTC. Our logs show the incident started on 10/21, 16:41 UTC and that during the 45 minutes that it took to resolve the issue 4.2% of customers in the West Europe region experienced an inability to query Log Analytics data.
Root Cause: The failure was due to a problem with one of our back end services.
Incident Timeline: 45 minutes - 10/21, 16:41 UTC through 10/21, 17:26 UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.
Initial Update: Monday, 21 October 2019 17:10 UTC
We are aware of issues within Log Analytics in the West Europe region and are actively investigating. Some customers may experience inability to query data.
Work Around: none at this time
Next Update: Before 10/21 18:30 UTC
We are working hard to resolve this issue and apologize for any inconvenience. -Jack Cantwell