The past couple of days, several critical vulnerabilities in Xen hypervisors have been announced. The vulnerabilities can be found here, but are not yet disclosed for security reasons.
Due to these vulnerabilities, our infrastructure providers have scheduled maintenance windows next Thursday March 5th between 4:00 AM and 8:00 AM UTC, where the hypervisors' datacenters that host our servers will reboot. We have created several fallbacks in order to keep the service up most of the time of these reboots, but there might be times that critical infrastructure goes down and the service will not be available.
We will do our best to keep interruptions to the minimum. Stay safe and be awesome.