Discourse is an open-source discussion platform. Prior to versions "3.3.4" on the "stable" branch and "3.4.0.beta5" on the "beta" branch, in specific circumstances, users could be added to group direct messages despite disabling direct messaging in their preferences. Versions "3.3.4" and "3.4.0.beta5" contain a patch for the issue. A workaround is available. If a user disables chat in their preferences then they cannot be added to new group chats.