Update - Our workaround has been successful, and has allowed calendar sync to resume for the affected users.
We continue to observe the elevated error rate on Microsoft's API, and will not be able to fully resolve the issue until this underlying cause is fixed.
During this time:
We are unable to pick up changes to affected users' calendar lists and may have an outdated view of secondary calendars as a result.
Users connecting Outlook.com calendar accounts to Cronofy for the first time may have issues getting successfully connected.
While Microsoft hasn't acknowledged the issue yet, this has been raised by other integrators, for example:
https://learn.microsoft.com/en-us/answers/questions/2279133/getting-500-response-errors-to-get-me-calendars-al
https://github.com/microsoftgraph/microsoft-graph-explorer-v4/issues/3861
We will continue to monitor, and shall update when there are notable changes or at least by 9AM UTC tomorrow, June 3rd.
Jun 02, 2025 - 17:12 UTC
We continue to observe the elevated error rate on Microsoft's API, and will not be able to fully resolve the issue until this underlying cause is fixed.
During this time:
We are unable to pick up changes to affected users' calendar lists and may have an outdated view of secondary calendars as a result.
Users connecting Outlook.com calendar accounts to Cronofy for the first time may have issues getting successfully connected.
While Microsoft hasn't acknowledged the issue yet, this has been raised by other integrators, for example:
https://learn.microsoft.com/en-us/answers/questions/2279133/getting-500-response-errors-to-get-me-calendars-al
https://github.com/microsoftgraph/microsoft-graph-explorer-v4/issues/3861
We will continue to monitor, and shall update when there are notable changes or at least by 9AM UTC tomorrow, June 3rd.
Jun 02, 2025 - 17:12 UTC
Monitoring - We've now fully rolled out our workaround and are monitoring the results as we work through our backlog of earlier failures.
Since we observed errors specifically when attempting to list calendars, as a temporary measure we are allowing the rest of the sync process to continue based on our latest copy of the user's calendar list. This allows calendar event data to resume syncing and avoids us having stale availability information for the affected users.
This is not a full resolution since it does mean that if affected users create or edit secondary calendars, we won't pick up the newly added calendars or new calendar names.
Jun 02, 2025 - 15:42 UTC
Since we observed errors specifically when attempting to list calendars, as a temporary measure we are allowing the rest of the sync process to continue based on our latest copy of the user's calendar list. This allows calendar event data to resume syncing and avoids us having stale availability information for the affected users.
This is not a full resolution since it does mean that if affected users create or edit secondary calendars, we won't pick up the newly added calendars or new calendar names.
Jun 02, 2025 - 15:42 UTC
Identified - We've found that we are seeing errors only from a particular API call which we use to list calendars, and have seen success with a limited rollout of a workaround that allows the rest of the sync process to continue. We are watching its progress and increasing our confidence in order to roll this out further.
Jun 02, 2025 - 15:04 UTC
Jun 02, 2025 - 15:04 UTC
Update - We've found that approximately one third of Outlook.com calendars are being affected. We do not believe a change our side has caused the elevated errors, but nor has Microsoft acknowledged an incident on their side.
We are continuing to investigate the affected cohort, and which API calls are affected, in case there is any workaround we can implement on our side.
Jun 02, 2025 - 12:33 UTC
We are continuing to investigate the affected cohort, and which API calls are affected, in case there is any workaround we can implement on our side.
Jun 02, 2025 - 12:33 UTC
Investigating - We've identified that a cohort of Outlook.com profiles are seeing an increased error rate when we communicate with Microsoft's APIs, causing sync failures for those affected.
We're investigating the root cause and will update this incident as we understand more.
Jun 02, 2025 - 11:59 UTC
We're investigating the root cause and will update this incident as we understand more.
Jun 02, 2025 - 11:59 UTC
Scheduler
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Major Calendar Providers
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Apple
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Google
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Microsoft 365
Operational
Outlook.com
Degraded Performance
Conferencing Services
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GoTo
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Zoom
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Maintenance
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Scheduled Maintenance
Database server upgrades in all data centers except Singapore Jun 8, 2025 07:00-09:00 UTC
We will be upgrading our database servers in all data centers except Singapore.
These upgrades require a failover to the new database servers, therefore there will be up to three minutes of disruption when this happens. We will upgrade the servers one data center at a time and will begin the first upgrade shortly after 07:00 UTC. We expect the upgrades to be completed by 09:00 UTC on Sunday, 8th June 2025.
We will provide notifications as this maintenance progresses via our status page.
If you have any questions, please email support@cronofy.com.
Posted on May 30, 2025 - 16:37 UTC
These upgrades require a failover to the new database servers, therefore there will be up to three minutes of disruption when this happens. We will upgrade the servers one data center at a time and will begin the first upgrade shortly after 07:00 UTC. We expect the upgrades to be completed by 09:00 UTC on Sunday, 8th June 2025.
We will provide notifications as this maintenance progresses via our status page.
If you have any questions, please email support@cronofy.com.
Posted on May 30, 2025 - 16:37 UTC