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

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

User impact: Users may have been unable to view free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users may have seen an "Unknown" status for the external Gmail contacts.

Final status: We've received confirmation from additional users that were previously reporting this issue that our mitigation steps have successfully resolved this event.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

End time: Friday, June 12, 2026, at 10:00 AM UTC

Root cause: Basic Authentication credentials weren’t being correctly forwarded to the third-party service, resulting in failures when obtaining free/busy status responses, which resulted in impact.

Next steps: - We're reviewing the flow of Basic Authentication credentials to better understand this impact and prevent similar future occurrences.

This is the final update for the event.

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

User impact: 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.

Current status: The deployment of our fix has completed as expected and we've received confirmation from a subset of users that this has successfully resolved impact. We're reaching out to additional users that were previously reporting this issue to ensure that this event has been fully remediated.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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

Next update by: Monday, June 15, 2026, at 7:30 PM UTC

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

User impact: 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.

Current status: Following our successful internal testing and validations we've deployed our solution. The deployment is approximately 81 percent complete, and user impact is expected to be addressed as it progresses. Our fix deployment timeline estimates it will have completed and that the impact will be remediated by our next scheduled communication update.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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

Next update by: Friday, June 12, 2026, at 8:30 PM UTC

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

User impact: 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.

Current status: We’ve initiated the deployment of our fix to our internal testing environment after addressing a previous blocker, which caused some delay. We're anticipating the validation process should complete by our next scheduled update, at which point we'll look to confirm a timeline for the full deployment.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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

Next update by: Tuesday, June 09, 2026, at 8:30 PM UTC

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

User impact: 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.

Current status: After identifying a new path for our deployment, we've determined that our fix will require an additional level of validations so we can ensure its deployment doesn't introduce any unexpected problems to the service. We're expecting more clarity into the timeline for our fix deployment and the remediation of the impact will be available once these tests have confirmed its viability.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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

Next update by: Friday, June 05, 2026, at 8:30 PM UTC

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

User impact: 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.

Current status: We've completed the validation of our fix; however, we've identified that a separate issue is preventing deployments from initiating within the affected infrastructure. We're working to resolve this separate issue in order to deploy our fix and remediate impact, and we'll aim to provide a timeline for this process as one becomes available.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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 update by: Thursday, June 04, 2026, at 8:30 PM UTC

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

User impact: 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.

Current status: Our internal validation of the fix is ongoing as we work to ensure efficacy and confirm no adverse effects. We expect to have a timeline for the fix deployment with our next scheduled communication update.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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 update by: Wednesday, June 03, 2026, at 8:30 PM UTC

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

User impact: 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.

Current status: Our internal validation process for the fix has been delayed due to a deployment pipeline issue but should be underway shortly. We're expediting this process and we're hopeful it will complete on Tuesday, June 2, 2026. Once complete, we'll provide an estimate on the fix deployment timeline to all affected environments.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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 update by: Tuesday, June 02, 2026, at 8:30 PM UTC

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

User impact: 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.

Current status: We've identified that 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. We’ve updated the Root cause section of this communication to more accurately reflect this source of impact. We're validating a fix in our internal testing environment aimed at correcting the credential forwarding problem and will provide a timeline for its safe deployment and subsequent impact remediation as one becomes available.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

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 update by: Monday, June 01, 2026, at 10:30 PM UTC

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

User impact: 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.

Current status: We've confirmed the full deployment of our solution; however, we've identified through internal metrics and user feedback that impact is persisting. We're examining fresh logs from a subset of affected users to gain further insight and inform our next steps.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Next update by: Friday, May 29, 2026, at 10:00 PM UTC

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

User impact: 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.

Current status: Our solution is approximately 95 percent saturated throughout the affected environment and should already be alleviating impact for the bulk of affected users. We're working with a subset of affected users to validate the efficacy of our solution and obtain additional trace logs capturing the impact should this issue continue to be reproducible, in order to determine any further mitigative actions that may be required to resolve 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.

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Root cause: A feature was recently disabled to mitigate an unrelated event, resulting in this impact.

Next update by: Friday, May 29, 2026, at 12:30 AM UTC

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

User impact: 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.

Current status: We've begun the deployment of our solution to the affected environment, and the rate of progress indicates it's on track to complete by the time of our next scheduled update.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Root cause: A feature was recently disabled to mitigate an unrelated event, resulting in this impact.

Next update by: Thursday, May 28, 2026, at 7:30 PM UTC

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

User impact: 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.

Current status: We've initiated the deployment of our fix to our internal environment for final validations. Once complete, we'll proceed with deploying the fix to the broader affected environment. We anticipate this may take until Wednesday, May 27, 2026 to complete, and will provide an update on the deployment timeline with our next scheduled communication update.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Root cause: A feature was recently disabled to mitigate an unrelated event, resulting in this impact.

Next update by: Tuesday, May 26, 2026, at 7:30 PM UTC

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

User impact: 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.

Current status: We've completed the development of our code fix, and validation of the fix within our internal testing environment is underway. We'll provide a timeline for deployment as one becomes available.

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

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Root cause: A feature was recently disabled to mitigate an unrelated event, resulting in this impact.

Next update by: Friday, May 22, 2026, at 7:30 PM UTC

Title: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar

User impact: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users are seeing an "Unknown" status for the external Gmail contacts.

Current status: We've received the report from your representatives that the script we provided to run as a possible workaround hasn't successfully mitigated the issue. We're now in the process of developing a code fix to fully remediate the impact.

Scope of impact: Your organization is impacted by this event, and all users attempting to view free/busy status for Gmail contacts in their Exchange Online calendars are affected.

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Root cause: A feature was recently disabled to mitigate an unrelated event, resulting in this impact.

Next update by: Wednesday, May 20, 2026, at 7:00 PM UTC

Title: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar

User impact: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users are seeing an "Unknown" status for the external Gmail contacts.

Current status: We determined a feature was recently disabled to mitigate an unrelated event, which resulted in a regression for this scenario. We've reached out to your organization and provided a script to run to address this issue, and we're awaiting confirmation that this action successfully alleviates impact.

Scope of impact: Your organization is impacted by this event, and all users attempting to view free/busy status for Gmail contacts in their Exchange Online calendars are affected.

Start time: Monday, May 11, 2026, at 7:01 AM UTC

Root cause: A feature was recently disabled to mitigate an unrelated event, resulting in this impact.

Next update by: Monday, May 18, 2026, at 7:00 PM UTC

Title: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar

User impact: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users are seeing an "Unknown" status for the external Gmail contacts.

Current status: We've discovered a similar ongoing service incident and are working to confirm correlation with that event as a part of our root cause investigation. We're continuing to leverage the documentation provided by your organization, such as the HTTP Archive format (HAR) logs, as a part of this active investigation.

Scope of impact: Your organization is impacted by this event, and all users attempting to view free/busy status for Gmail contacts in their Exchange Online calendars are affected.

Next update by: Friday, May 15, 2026, at 7:00 PM UTC

Title: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar

User impact: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users are seeing an "Unknown" status for the external Gmail contacts.

Current status: We're continuing our review of support case data while analyzing recent service updates and service-side logging to progress the investigation.

Scope of impact: Your organization is impacted by this event, and all users attempting to view free/busy status for Gmail contacts in their Exchange Online calendars are affected.

Next update by: Thursday, May 14, 2026, at 11:30 PM UTC

Title: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar

User impact: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar.

More info: Affected users are seeing an "Unknown" status for the external Gmail contacts.

Current status: We're reviewing support case details to better understand the impact scenario and determine our next diagnostic steps.

Scope of impact: Your organization is impacted by this event, and all users attempting to view free/busy status for Gmail contacts in their Exchange Online calendars are affected.

Next update by: Thursday, May 14, 2026, at 6:30 PM UTC

Title: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar

User impact: Users aren't seeing free/busy status for Gmail users within the Exchange Online calendar.

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