I contacted CIC about the problem, this is what I received in return (they were pretty quick to reply):
The error message you described in your email is the result of a periodic technical problem. That means that you may still be able to access IRCC's online services before the situation is resolved on a permanent basis. Please try again.
We apologize for any inconvenience that this may have caused. Rest assured that the responsible department is currently making all the necessary efforts to resolve the issue as quickly as possible.