We have recently been made aware of a critical security update to the Xen hypervisor software, which we use as the foundation of the File Sanctuary Cloud. We will be applying this update on Thursday, September 14, 2017 between 17:00 and 19:00 BST. This update requires us to reboot each node in our cloud, which will involve customer Cloud Servers being shut down and restarted too. As a result there will be brief periods when Cloud Servers, Web and Email Hosting accounts, and our customer portal become temporarily unavailable. We do not expect any service to be down for the entire maintenance window, most services will only go down for a few minutes before they come back online.