Your forum has been updated to Discourse 3.0, a new major release, including many significant changes like the integrated chat and the new sidebar. The full list of new features and bug fixes can be found here.
There are a few things that have changed with respect to certain plugins, which might affect your forum.
The Sitemap plugin has been moved into core, so although you will not see it as a separate plugin any longer, you will still be able to leverage its full functionality.
The Topic List Previews plugin has been deprecated. We have installed the topic list previews sidecar plugin instead, and the main functionality has been moved to the topic list previews theme component. If you have not installed that, you can find the installation instructions here.
The Quick Messages plugin has been deprecated. Chat is a good replacement.
The Retort plugin has been deprecated. The new Reactions plugin is a good replacement.
The Question Answer plugin has been deprecated. It is being replaced with the Post Voting plugin which has around the same functionality.
The Canned Replies plugin has been deprecated and replaced by the templates plugin which has much broader functionality and allows for private templates as well. We have already migrated your existing canned replies to templates.
If you have any questions, feel free to contact us.