Mattermost change history: Unable to create new workspaces

Mattermost reported a major outage preventing new workspace creation, affecting Cloud Sign-Up, Cloud Workspaces and Sign-Up, citing a cloud-provider outage in us-east-1. It started at 2021-12-07 16:37 UTC and was resolved at 2021-12-07 22:45 UTC, lasting 6 h 7 min; all systems were reported operational.