We've confirmed that all systems are back to normal with no customer impact as of 12/18, 10:40 UTC. Our logs show the incident started on 12/17, 21:40 UTC and that during the ~13 hours that it took to resolve the issue some customers would have experienced an unauthorized exception message while running log search queries in Azure portal. The Log Analytics portal users would also have encountered with unauthorized exception in OMS portal.
Root Cause: The failure was due to authentication issue with one of our backend dependent service.
Incident Timeline: ~13 Hours - 12/17, 21:40 UTC through 12/18, 10:40 UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.
Initial Update: Tuesday, 18 December 2018 09:30 UTC
We are aware of issues within Log Analytics and are actively investigating. Some customers may experience data access issue in Azure and OMS Portal for Log Analytics.
Work Around: NA
Next Update: Before 12/18 11:30 UTC
We are working hard to resolve this issue and apologize for any inconvenience.