The Sentry 9 release was a long time in the making and involved significant changes to various features, including Teams, Issue Owners, Settings Pages Redesign, and Environments. The update to Teams added the option to assign multiple teams to an individual project and team ownership of issues or sections of codebase. This enabled the development of the Issue Owners feature, which allows assigning different parts of a codebase to teams or individuals for notification purposes. The Settings Pages Redesign improved performance, navigation, and consistency, while also introducing a new breadcrumb navigation system. The Environments feature provides an implicit prioritization mechanism based on deployment environments, allowing users to drill down to errors by environment. These features were developed with the goal of making Sentry more user-friendly and actionable for developers, while also improving performance and data storage efficiency.