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EX1233142 — Advisory

Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

Service degradation
Exchange Online
E-Mail and calendar access
Started
08 Dec 2025 03:04 GMT
Last Microsoft update
01 May 2026 01:46 GMT+1
Data freshness
Live — checked 13:07 GMT+1
Impact
Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.
Incident Timeline
01 May 2026 01:45 GMT+1

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Current status: We're continuing to monitor the incremental progress of the deployment; however, more time is needed before we can provide an accurate timeline for resolution.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings outside the room's working hours in Exchange Online may be impacted. This information may be updated as our investigation continues.

Start time: Monday, December 08, 2025, at 3:04 AM UTC

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets the meeting rooms' default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Wednesday, May 13, 2026, at 2:30 AM UTC

24 Apr 2026 00:49 GMT+1

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Current status: The incremental rollout of the fix is ongoing and we’re continuing to monitor its progress to ensure it completes as expected. We’ll provide an estimation for full impact resolution when one becomes available.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings outside the room's working hours in Exchange Online may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets the meeting rooms' default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Friday, May 1, 2026, at 1:00 AM UTC

16 Apr 2026 00:09 GMT+1

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Current status: The deployment of our fix is progressing, and our review of service health telemetry shows continued signs of improvement. While we continue to monitor the deployment as it propagates throughout the affected service environment, we anticipate that users will experience relief from impact whilst the time we work to ascertain a full remediation timeline.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings outside the room's working hours in Exchange Online may be impacted. This information may be updated as our investigation continues.

Start time: Monday, December 8, 2025, at 3:04 AM UTC

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets the meeting rooms' default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Friday, April 24, 2026, at 1:00 AM UTC

02 Apr 2026 00:31 GMT+1

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Current status: The deployment of the fix is ongoing and we're continuing to monitor as it progresses.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings outside the room's working hours in Exchange Online may be impacted. This information may be updated as our investigation continues.

Start time: Monday, December 8, 2025, at 3:04 AM UTC

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets the meeting rooms' default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Thursday, April 16, 2026, at 1:00 AM UTC

27 Mar 2026 01:39 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Current status: We’re continuing to monitor the deployment of our fix as it progresses and we anticipate it’ll reach completion by mid-April.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings outside the room's working hours in Exchange Online may be impacted. This information may be updated as our investigation continues.

Start time: Monday, December 8, 2025, at 3:04 AM UTC

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets the meeting rooms' default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Thursday, April 2, 2026, at 1:00 AM UTC

18 Mar 2026 02:02 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Current status: Based on feedback received regarding this communication, we've edited the More info, Scope of impact, and Root cause sections of this communication to align with our current understanding of the affected scenario. Additionally, we've completed validation of the fix and have begun its deployment. We're monitoring as it progresses and will provide a completion timeline when one becomes available.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings outside the room's working hours in Exchange Online may be impacted. This information may be updated as our investigation continues.

Start time: Monday, December 8, 2025, at 3:04 AM UTC

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets the meeting rooms' default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Friday, March 27, 2026, at 3:00 AM UTC

10 Mar 2026 01:39 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Impact is specific to users who have not updated their working hours and time zone to reflect accurately. To avoid this issue, users can manually edit their working hours and ensure their time zone is accurate.

Current status: We're continuing our efforts to validate the fix in our internal testing environment; however, more time is needed to complete this process and confirm that the fix fully addresses the impact. Once ready, we will begin the full deployment to the remaining affected environment.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online who have not updated their working hours or time zone may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets users default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Wednesday, March 18, 2026, at 3:00 AM UTC

09 Mar 2026 01:47 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Impact is specific to users who have not updated their working hours and time zone to reflect accurately. To avoid this issue, users can manually edit their working hours and ensure their time zone is accurate.

Current status: We're continuing to deploy the fix in our internal test environment and completing final validations prior to deploying it to the remaining affected environments.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online who have not updated their working hours or time zone may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets users default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Tuesday, March 10, 2026, at 3:00 AM UTC

07 Mar 2026 00:51 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Impact is specific to users who have not updated their working hours and time zone to reflect accurately. To avoid this issue, users can manually edit their working hours and ensure their time zone is accurate.

Current status: We're working to ensure that our fix has mitigated the impact as expected and are running tests to confirm whether any additional changes need to be made.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online who have not updated their working hours or time zone may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets users default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Monday, March 9, 2026, at 2:00 AM UTC

02 Mar 2026 23:48 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Impact is specific to users who have not updated their working hours and time zone to reflect accurately. To avoid this issue, users can manually edit their working hours and ensure their time zone is accurate.

Current status: We’ve developed a fix that will implement two changes to resolve the underlying issue. First, the fix will prevent the Exchange Online time zone from automatically setting users working hours to Pacific Standard Time. Secondly, the fix will allow users to select meeting rooms outside of their working hours if the room is actually available. We're preparing to deploy the fix and anticipate it will be fully deployed and the impact remediated by our next scheduled update. Additionally, to immediately resolve the issue, users can manually update their time zone and working hours to reflect accurately.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online who have not updated their working hours or time zone may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings contains a code complication which automatically sets users default working hours to appear in Pacific Standard Time instead of their accurate time zone.

Next update by: Saturday, March 7, 2026, at 1:00 AM UTC

27 Feb 2026 20:35 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

Current status: We’re continuing to review our options to most efficiently and permanently resolve this issue. We anticipate having a solidified remediation plan and estimate for the delivery of our fix by our next scheduled update.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings didn't account for certain working hour configurations, resulting in impact.

Next update by: Tuesday, March 3, 2026, at 1:00 AM UTC

26 Feb 2026 20:43 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

Current status: We've determined that a recent expansion of the feature logic used to book rooms for scheduled meetings didn't account for certain working hour configurations, resulting in impact. We decided that instead of adding a new state to the UI, which would include "Outside of working hours," we’re focusing on improving the logic to correctly determine and display what times are considered in working hours, so that rooms appear in the correct state consistently across the interface.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Root cause: A recent expansion of the feature logic used to book rooms for scheduled meetings didn't account for certain working hour configurations, resulting in impact.

Next update by: Friday, February 27, 2026, at 9:30 PM UTC

25 Feb 2026 19:49 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected may be seen incorrectly changing from available to unavailable in Exchange Online.

Additionally, some users are seeing that room suggestions don’t consistently reflect configured working hours, especially before and after selecting a room.

While we're focused on remediation, impacted admins may be able to adjust meeting rooms to 24-hour availability within Exchange Online to prevent users from encountering impact.

Current status: We're preparing a code change to introduce a new state to the User Interface (UI), "Outside of working hours," alongside additional logic to correct this issue. We're working to determine a timeline for the code change development along with testing and validation as we continue.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Thursday, February 26, 2026, at 9:30 PM UTC

25 Feb 2026 10:05 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected may be seen incorrectly changing from available to unavailable in Exchange Online.

Additionally, some users are seeing that room suggestions don’t consistently reflect configured working hours, especially before and after selecting a room.

While we're focused on remediation, impacted admins may be able to adjust meeting rooms to 24-hour availability within Exchange Online to prevent users from encountering impact.

Current status: As part of our ongoing investigation, we’ve identified a configuration‑related service scenario affecting room availability and have shared a temporary workaround in the More Info section to help prevent further impact. We’re continuing to work to identify steps toward a longer-term resolution.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Wednesday, February 25, 2026, at 9:00 PM UTC

25 Feb 2026 03:26 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected may be seen incorrectly changing from available to unavailable in Exchange Online.

Additionally, some users are seeing that room suggestions don’t consistently reflect configured working hours, especially before and after selecting a room.

While we're focused on remediation, impacted admins may be able to adjust meeting rooms to 24-hour availability within Exchange Online to prevent users from encountering impact.

Current status: We've identified an underlying code conflict scenario, which we suspect is contributing to the impact. Due to the complexity of the scenario, we're anticipating it may take some additional time before we can identify a timeline and route to remediation.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Wednesday, February 25, 2026, at 10:30 AM UTC

18 Feb 2026 03:27 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected is incorrectly changing from available to unavailable in Exchange Online.

Additionally, some users are seeing that room suggestions don’t consistently reflect configured working hours, especially before and after selecting a room.

Current status: As we continue our investigation to isolate the origin of this issue, we’re reaching out to some affected users to validate and confirm whether their time zone settings are configured correctly as a potential solution to this problem. Additionally, regarding room suggestions not reflecting the configured working hours, we suggest that admins adjust the work hours to 24 hours to prevent this issue from occurring as we focus on developing a long-term solution.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Wednesday, February 25, 2026, at 3:30 AM UTC

17 Feb 2026 17:36 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected is incorrectly changing from available to unavailable in Exchange Online.

Current status: While our review of the HAR network trace logs is ongoing to progress our root cause investigation, we're assessing the efficacy of some potential remediation actions in recovering the scenario.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Wednesday, February 18, 2026, at 3:30 AM UTC

16 Feb 2026 06:20 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected is incorrectly changing from available to unavailable in Exchange Online.

Current status: We're continuing to analyze the HAR logs and screenshots of the issue to isolate the root cause of the issue.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Tuesday, February 17, 2026, at 7:00 PM UTC

16 Feb 2026 05:30 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected is incorrectly changing from available to unavailable in Exchange Online.

Current status: We're reviewing HTTP Archive format (HAR) logs and screenshots of the issue to help with the investigation and to determine our next troubleshooting steps.

Scope of impact: Any users that are trying to select a meeting room when scheduling meetings in Exchange Online may be impacted. This information may be updated as our investigation continues.

Next update by: Monday, February 16, 2026, at 6:30 AM UTC

16 Feb 2026 05:07 GMT

Title: Some users may see that when selecting a meeting room when scheduling meetings, it changes from available to unavailable

User impact: Users may see that after selecting a meeting room when scheduling meetings, it changes from available to unavailable.

More info: Specifically, the meeting room selected is incorrectly changing from available to unavailable in Exchange Online.

Current status: We're investigating a potential issue with Exchange Online and checking for impact to your organization. We'll provide an update within 30 minutes.