Incident resolved - At 7:26PM ET we executed an operation on our database which caused some critical site settings data to become inaccessible to our applications. All sites and stores were affected. For many sites, visitors saw a cached version of the site. During this time, sites could not be edited and shopping was not possible.
We started restoring sites at 9:22PM ET. As of 9:56PM ET, the restore operations were completed and all affected websites are loading again. If you are having any issues with settings on your site or store, please contact Customer Support - https://support.squarespace.com/hc/requests/new