User impact: Users may experience various issues when using the Microsoft Defender and Exchange Online Protection services.

More info: Impact includes, but is not limited to:
– Delayed quarantined email notifications
– Delayed or erroring policy change propagation
– Delayed detection, message tracing, and reporting
– Delayed Advanced hunting reports

Current status: Our efforts to revert the update are continuing; however, it’s taking longer than initially expected to complete for all users. We’re actively exploring options to expedite the reversion, and we’ll provide an estimated time to resolution as soon as one becomes available.   

Scope of impact: Any user hosted out of the affected infrastructure may experience impact when attempting to perform any of the functionalities outlined in the More info section of this communication.

Start time: Friday, October 20, 2023, at 6:00 AM UTC

Root cause: A recent update led to a code regression within a portion of infrastructure responsible for facilitating some Microsoft Defender and Exchange Online protection functionalities.

Next update by: Saturday, October 21, 2023, at 12:30 AM UTC