<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=590798) </details> <!--IssueSummary end--> In GitLab 19.0, we plan to remove bundled Mattermost from the Linux package. Mattermost was first bundled with GitLab in 2015 as an open source team messaging solution, with GitLab SSO included to support the integration. Since then, Mattermost has significantly matured its own packaging and deployment options, and adoption of the bundled Mattermost among GitLab customers has remained relatively low. With Mattermost v11, [Mattermost has deprecated GitLab SSO from their free offering](https://forum.cloudron.io/topic/14298/upcoming-removal-of-gitlab-sso-in-mattermost-v11-suggestion-for-cloudron). Given this change, the maturity of Mattermost standalone deployment options, and the low adoption in our customer base, we are removing Mattermost from the Linux package. If you currently use Mattermost bundled with GitLab, refer to [Migrating from GitLab Omnibus to Mattermost Standalone](https://docs.mattermost.com/administration-guide/onboard/migrate-gitlab-omnibus.html) in the Mattermost documentation for migration instructions and available Mattermost editions. Please share your feedback, concerns, or use cases related to this change.