Is Cronofy Down?

Microsoft 365 was degraded from approximately 17:30 UTC, Thursday 12th November until 13:30 UTC, Friday 13th November. A large number of sync operations between Cronofy and Microsoft were failing, leading to delays in changes being reflected. Communication with Microsoft 365 services has recovered, and all real-time Cronofy operations are working normally. We have processed every change made to an event via Cronofy during the incident. Event creates, updates and deletes now appear in Microsoft 365 calendars as normal. We are syncing changes made in the calendar into Cronofy again too. Because the outage was long, we are also running extra syncs to confirm that every calendar is fully up to date. This work runs as fast as Microsoft's rate limits allow. While we are doing extra work to validate the integrity of calendar data, until it is finished, a small number of results could be based on stale calendar data. As most people couldn’t interact with their calendars during the outage, we believe this is unlikely but want to be certain. No data has been lost, and no action is needed from you. At this point, we believe normal function is restored, and we are marking this incident as resolved; if you have any queries, please contact us at support@cronofy.com --- [2026-11-13T14:10:22.138Z] (monitoring) We're seeing improvement: syncs with Microsoft are succeeding in much greater numbers. We are processing the backlog of changes to bring calendars fully back in sync. --- [2026-11-13T12:05:13.294Z] (monitoring) We are continuing to monitor for any further issues. --- [2026-11-13T11:56:44.441Z] (monitoring) While we wait for the Microsoft outage to be resolved, here is what you can expect from your Cronofy operations: - We are retrying all creation and updates to events. As Microsoft restores service, these will begin to sync into calendars as usual. - Availability Queries still work, and are based on our best knowledge of each calendar. Calendar data from Microsoft can not be guaranteed to be up to date at the moment. However, as no one can edit their calendars at the moment, this is a low risk. - Push Notifications for calendar changes are being sent as normal. You will be seeing lower levels now because of the lack of changes being received from Microsoft. There will be higher levels later when sync operations resume. - Once connection is restored, Cronofy will automatically reconcile changes to events to bring the calendar back up to date. This is the same operation as when a calendar has been disconnected for a period and then reconnected. You do not need to take any action, and no data will be lost; all changes will eventually sync as soon as we are able. We are continuing to monitor https://status.cloud.microsoft/ and our own telemetry, and will update again once we see normal operations resuming. --- [2026-11-13T00:16:26.302Z] (monitoring) We are still monitoring, waiting for Microsoft to restore service fully. We are going to stop posting updates for now, until we see the incident resolved. Our service will continue to sync as much as possible, and retry any changes that failed. Please watch https://status.cloud.microsoft/ for updates from Microsoft on the resolution of the incident. --- [2026-11-12T22:03:40.327Z] (monitoring) We have still seen no improvement yet. Sync of Microsoft calendars remains degraded - about 40% of our communications to Microsoft are working, and any failed calls are being retried until they succeed. Microsoft are reporting under issue reference EX1550543, which you can follow at https://status.cloud.microsoft We will update this status when we see some improvement or in another 2 hours. --- [2026-11-12T19:56:35.648Z] (monitoring) We are continuing to monitor the situation but have seen no improvement yet. Microsoft are reporting under issue reference EX1550543, which you can follow at https://status.cloud.microsoft We will update this status when we see some improvement or in 2 hours. --- [2026-11-12T18:51:59.140Z] (monitoring) We are continuing to monitor the situation. Sync to Microsoft 365 calendars is degraded, so there is some delay between events appearing in calendars. Other providers are not impacted. We will update this status when we see some improvement, or in an hour. --- [2026-11-12T18:27:58.651Z] (monitoring) This looks to be as a result of a wider outage with Microsoft's services that has been given issue reference EX1550543. We'll continue to monitor. --- [2026-11-12T18:07:40.607Z] (investigating) We are observing Microsoft 365 calendar APIs returning higher error rates and investigating the impact. This may affect how quickly changes to calendars are observed and our ability to push events.

Google Meet join success is back to normal since our most recent updates and we consider this incident resolved. On 12th November we saw a large uptick in Google Meet failures at the meeting join stage which we reported as access_denied. We believe Google rolled out a change in behavior over time, as looking back over our telemetry we see that this would have been visible earlier throughout November at a lower level. As part of the fixes deployed, we have increased our monitoring coverage and sensitivity in this area to better handle future similar cases should they occur. --- [2026-11-13T12:44:45.692Z] (monitoring) Our improvements today have had positive results so far. We're continuing to monitor Google Meet success rates closely. --- [2026-11-13T09:47:00.347Z] (identified) A further improvement to Google Meet Meeting Agents released this morning and we are monitoring its impact on overall success rates in our environments --- [2026-11-12T18:00:13.581Z] (identified) We've implemented an improvement to our meeting join logic which has improved our success rate, but not entirely eliminated the issue. We're continuing to make further improvements and will post updates as they release. --- [2026-11-12T14:57:55.099Z] (investigating) We are investigating an increased failure rate in Meeting Agents joining Google Meet calls, resulting in us reporting an access_denied status for impacted cases. Other meeting providers are unaffected.

Cronofy are aware of two recently published PHP vulnerabilities, CVE-2026-109618 & CVE-2026-109619. We can confirm that we do not make use of PHP and are therefore unaffected by these vulnerabilities. Regarding usage of our PHP SDK, we strongly recommend that you upgrade to a version of PHP that includes patches for the two identified vulnerabilities. For further reading please refer to PHP’s documentation: https://www.php.net/archive/2026.php#2026-10-21-5 Please contact support@cronofy.com with any questions.