On Sunday 17th November, 10am UTC we will be starting a major operating system upgrade across all our systems. We expect this upgrade to take several hours until completion, with check server upgrades taking up to 48 hours thereafter.
We will perform this maintenance incrementally, such that very minimal downtime (several minutes) is expected throughout the maintenance period as servers are switched. We will update this status page throughout the maintenance, and especially before the core systems are updated which will cause the short outages described above.
Check servers will also be updated incrementally, such that at most one location may be inoperative for a short period as it is upgraded. Note that if you have our recommended minimum of 3 or more locations assigned to your checks, this will ensure your checks continue to function correctly throughout the periods where each location is upgraded.