We are excited to introduce the Amazon WorkSpaces restore feature that enables you to rollback your WorkSpace to its last known healthy state. The new feature can serve as an easy recovery option to mitigate the impact of inaccessible WorkSpaces caused by incompatible 3rd party updates on Workspaces.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/09/amazon-workspaces-introduces-workspaces-restore-to-healthy-state/