[Update 2x: Apple has also acknowledged the outage on its system status page noting that it began last night and may still be ongoing.]
No word on Apple’s official iCloud system status page, but the Calendar and Reminders web apps on iCloud.com are currently down as several readers have pointed out. We’ve tested it here and the above error was returned. Apple’s iMessage service suffered a similar outage earlier this week with users reporting widespread downtime. Other iCloud web apps appear to be working properly. We’ll keep an eye on the outage and update if anything changes, but if you’re seeing the outage it’s not just you.