Microsoft is reporting that some users may have difficulty accessing Outlook on the web, and DownDetector appears to be confirming that this is an issue.

Microsoft’s advisory reads:

Users may be unable to access Outlook on the web.

EX289214, Exchange Online, Last updated: October 5, 2021 12:42 AM
Estimated start time: October 4, 2021 11:42 PM

October 4, 2021 11:54 PM

Title: We’re looking into a potential problem. User Impact: We’re investigating the potential end-user impact. We’re investigating a potential issue and checking for impact to your organization. We’ll provide an update within 60 minutes.

October 5, 2021 12:24 AM

Current status: We’re analyzing system logs to determine the source of impact. Scope of impact: Impact is specific to users who are served through the affected infrastructure. Start time: Monday, October 4, 2021, 11:42 PM (10:42 PM UTC) Next update by: Tuesday, October 5, 2021, 1:30 AM (12:30 AM UTC)

October 5, 2021 12:42 AM · Quick update

We’re gathering and analyzing diagnostic data from the impacted services to determine the cause of the problem. This quick update is designed to give the latest information on this issue.

While some users are seriously affected, the issue appears to be localized and only affect users who are using the specific infrastructure. Microsoft is still gathering data and investigating.

Update: Microsoft has confirmed that the issue was caused by a configuration issue, which they have now reversed. That appears to have resolved the problem.

Are any of our readers affected? Let us know below.