Microsoft 365 Alert – Service Degradation – Exchange Online – Users may be unable to view free/busy status for Gmail users within the Exchange Online calendar – ONGOING

Announcements Shagufta Naaz

22/05/2026 08:31:00 AM

NHSmail Reference: INC46832712

Microsoft Reference: EX1310533

Issue Status: RESOLVED

Issue Description: Users may be unable to view free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users may see an “Unknown” status for the external Gmail contacts.

Final Update: 16/06/2026 09:37:00 AM – Microsoft has received confirmation from additional users that were previously reporting this issue that their mitigation steps have successfully resolved this event.

Scope of impact: Impact is specific to any user attempting to view free/busy status for Gmail contacts in their Exchange Online calendars.

Root cause: Basic Authentication credentials aren’t being correctly forwarded to the third-party service, resulting in the failures to obtain free/busy status responses and causing impact.

Next steps: Microsoft is reviewing the flow of Basic Authentication credentials to better understand this impact and prevent similar future occurrences.