Intuit Quickbooks Online is down and they have a refreshingly retro way of communicating system status to their customers:

Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, [email protected] and inform them of the time the error occurred, and anything you might have done that may have caused the error.

https://qbo.intuit.com/login?redirect=true