Cronofy had 18 outages in the last 2 years totaling 61h 36m of downtime — averaging 0.7 incidents per month.
There were 18 Cronofy outages since May 22, 2025 totaling 61h 36m of downtime. Each is summarised below — incident details, duration, and resolution information.
Between 03:08 UTC and 03:10 UTC we observed increased API error rates in our US data center. During this time, customers may have received 500 Internal Server Error responses. Since that time, error rates have returned to normal levels. These errors were caused by a read-only database server going through an automated recovery process.
We've seen that Google's API is returning an increased number of 503 errors when we attempt to sync calendars. This is affecting a small percentage of calendars, and some users may see delayed calendar syncs as a result. We're continuing to monitor and investigate.
We are seeing signs of improvement from Google's side -- error rates have improved a great deal but are not yet quite back to normal levels. We continue to monitor the situation.
Google have identified an issue within their infrastructure which they're tracking at https://www.google.com/appsstatus/dashboard/incidents/KamjizntSiNtRETcBL2Q From our side, we're now seeing very low enough error rates that we don't think that users will experience any noticeable negative impact. We'll keep watching Google's incident until it's fully resolved.
Google has closed their incident and we've seen error rates remain low so are likewise marking this as resolved now.
We are aware of issues affecting our Google Chrome Extension preventing users from creating scheduling requests in Gmail. We are currently investigating and will provide an update as soon as possible.
We are still working to identify the exact root cause of the issue. We will provide further updates as soon as possible.
A recent Google Chrome update has changed a mechanism that our Gmail extension relies on. We are developing a fix that is compatible with this new mechanism. We will provide an update in a few hours or when we have an updated version of the extension ready.
We have submitted an updated version of the Chrome Extension to Google which contains a fix for this issue. The updated version will be available as soon as it has been checked and published by Google. We will provide an update once we confirmation of this from Google.
We have released version 0.22.25 of the Cronofy Chrome extension, fixing the issue. If you have any problems, please first check that both Google Chrome and the Cronofy Chrome extension are up to date. If you have any additional issues then please contact [email protected].
Between 12:52 and 12:55 we saw that calls to our API encountered a higher level of 500 Server Error responses than usual We have investigated this and it appears to relate to a period where we saw a large spike in traffic, a rapid drop and another spike in quick succession resulting in some temporary 500 errors. This is now resolved but we will continue monitoring for any further issues.
We are investigating an elevated level of failures for provisioning MS Teams Conferencing.
We are continuing to investigate - the issue is not impacting all customers but we are not yet seeing a pattern to the domains or events impacted.
We are still investigating; we are capturing additional logs to help us narrow down the failing population. Some conferences are being provisioned after automatically retrying, but still not as many as we'd expect.
We've found some evidence that other users of the Microsoft Graph API are experiencing the same issue; we're looking for anything that may let us mitigate the impact and we're reaching out to Microsoft for support.
We believe the root cause is a lack of generated URLs for a meeting when we call Microsoft Graph APIs. We are waiting for a response from Microsoft on the issue. Unfortunately the timing of this is out of our hands. We are also working on alternative ways to provision Teams meetings, but this will not provide a short term fix. We are continuing to work on finding a way to resolve, mitigate or provide an more reliable path to Teams provisioning. We will update this incident over the coming days as we make meaningful progress.
We have seen that our error rate provisioning MS Teams Conferencing has returned to normal, low levels since 16:10 UTC yesterday. Normal levels of service have resumed, and we're working to improve our monitoring so that similar issues are detected sooner in the future.
We are currently investigating degraded sync performance for Microsoft 365 as we are experiencing a much higher error rate than normal.
We believe this is related to a Microsoft incident (ID: MO1221364). We are keeping a close eye on how this progresses
We are continuing to monitor the situation, but have not seen any improvement so far
Between 22:00 and 01:15 UTC we saw elevated error rates when performing sync operations with Microsoft 365. Microsoft continues to work on a full resolution to the incident with ID MO1221364. However, the error rates we are now observing are back to normal levels.
We are currently investigating the cause of Google calendar sync degradation
Google's API error rate has dropped again and has been at normal levels for the past 10 minutes. We'll continue to monitor and confirm this holds out.
Between 18:15 UTC and 18:28 UTC, we observed elevated error rates, and Google Calendar users may have experienced delays with calendar reads and writes. Since 18:28 UTC, all Google Calendar operations have been functioning as normal.
Since 10:40 UTC we have observed an increased error rate for Apple calendar sync operations. We are still seeing more successes than failures but consider there to be enough failures to mark Apple as degraded. Our retry mechanisms appear to be doing their job, but changes to calendars may take longer to sync both to and from Apple as a result of the underlying errors. We are monitoring the situation.
Starting at 10:40 UTC we observed an elevated error rate when communicating with Apple's calendar service. Errors returned to regular levels by 11:35 UTC. Sync with Apple calendars may have taken longer both to and from Apple as a result of the underlying errors during this period.
We've observed an elevated rate of errors from Google's Calendar API and are investigating the scale and impact. Updates to and from Google Calendar profiles may see slight delays during this time. We are monitoring the situation.
Google is returning a higher rate of 5xx errors when we try to perform token refresh operations. Approximately 1/3rd of our attempts to refresh tokens are seeing this error. The increase in errors started approximately 14:57 UTC. It appears our normal mechanisms are allowing retries to be processed successfully, and limiting the impact to the wider service. Updates to and from Google Calendar profiles may see slight delays during this time. Google appear to have acknowledged the incident: https://www.google.com/appsstatus/dashboard/incidents/oFcAZTr4EVieF5Fr6Ee9
Google's API error rate has dropped again and held at a normal level for the past 10 minutes, and both read and write operations to Google Calendar profiles appear to be back to our normal level of performance. We'll continue to monitor and confirm this holds out.
API success rates have remained stable since our previous message, and Google have resolved their own incident: https://www.google.com/appsstatus/dashboard/incidents/oFcAZTr4EVieF5Fr6Ee9 Between the times of 14:57 UTC - 15:35 UTC, we saw elevated rates of errors, and Google Calendar users may have had slight delays to calendar reads and writes. Since 15:35 UTC everything has been functioning as normal.
We've identified that some Outlook.com profiles may be increased error rates when authenticating with Microsoft's APIs, causing sync failures for those affected. This appears to be related to an ongoing issue with Outlook.com We're investigating the root cause and will update this incident as we understand more.
We've ascertained that the issue isn't down to changes on our side and are tracking live issue with Outlook.com. Microsoft are reporting on this as Issue ID EX1112414. We can see that not all profiles are affected and that, of those that are, retries do eventually succeed. We'll continue to monitor and advise of any further changes.
Error rates remain fairly consistent. We're continuing to monitor and will advise of any further changes.
Error rates remain fairly consistent. We're continuing to monitor and will advise of any further changes.
Error rates remain fairly consistent and Microsoft are in the process of rolling out a fix. We've yet to see the effects of this, are continuing to monitor, and will advise of any further changes.
As of 16:30 UTC we're seeing service levels back at their expected levels and a drastic reduction in error rates. Outlook.com profiles are now authenticating consistently. Microsoft Issue ID EX1112414 remains open however and so we'll continue to monitor things for a while longer in the expectation that this issue is now resolved but just to be sure.
Microsoft Issue ID EX1112414 remains open however a preliminary root cause has been provided: "A recent service update to an authentication component is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability." We've seen no further issues since our previous update and error rates remain consistent with healthy operations so we're going to consider this incident resolved.
We are seeing a sudden increase in Google sync errors and are investigating.
The error rate has returned to normal. This does not align with any changes or operations on our side, and the error returned from Google suggests this may have been a temporary issue on their side. We are continuing to investigate to try and identify a root cause, as well as monitoring the situation for any further changes.
We are seeing the issue recur and are continuing to investigate.
Error rates have again returned to normal, and were affecting a fairly small number of operations spread across many accounts. We're continuing to investigate to try and find a pattern.
The error rate has remained low, but we are still investigating and monitoring.
Error rates are still low and sync is working as expected. We are continuing to monitor the situation.
Error rates have remained at normal levels and we believe the issue is over. After two increases in error rates, at 14:24 UTC and 14:45 UTC, Google sync has remained stable. A minority of sync operations failed and were retried, eventually completing successfully.
We are seeing an elevated number of errors from Google and we are investigating
Since 17:49 UTC we are receiving a greatly increased rate of API errors from Google. Many syncs are completing after retrying but customers may observe events taking slightly longer to appear in their calendars.
Google errors are remaining elevated. We have seen reports of other services also encountering issues with Google APIs and believe this to be related. We are continuing to investigate and monitor our services to be sure. We will update in ~30 minutes time if nothing substantial changes.
Google API calls have recovered and most are now succeeding. We are continuing to monitor the system to ensure this pattern continues. This issue is due to the following Google incident: https://status.cloud.google.com/incidents/ow5i3PPK96RduMcb1SsW#2c2sBHWU84yPDJ8y1ar4
We continue to see healthy syncs with Google. However the Google incident remains open, citing that some areas have recovered but a full mitigation has not taken place yet. We are leaving this incident open to reflect that disruption may still be possible until Google confirm the issue is fully mitigated or resolved. Google Cloud incident: https://status.cloud.google.com/incidents/ow5i3PPK96RduMcb1SsW#2c2sBHWU84yPDJ8y1ar4
Google API calls began to error at abnormally high rates from 17:49 UTC. Upon investigation, we did not find a common factor or pattern behind the failures but kept investigating and engages some fallback mechanisms to keep the platform stable. We began to find other reports of Google API issues, ultimately having this confirmed by Google: - Google Workspace incident: https://www.google.com/appsstatus/dashboard/incidents/Eab7zGLWSaUJyh9c9R9L - Google Cloud incident: https://status.cloud.google.com/incidents/ow5i3PPK96RduMcb1SsW#2c2sBHWU84yPDJ8y1ar4 We continued to monitor the system and confirmed that calendars were still syncing, albeit with occasional delays when syncs failed and had to be retried. At 18:48 UTC, API errors dropped drastically and returned to normal operational levels. We kept monitoring until we saw Google report the issue was resolved at 19:53 UTC.