Remove nodebb-plugin-extended-markdown from your package.json, looks like it isn't compatible.
When i try to access /groups/administrators (group is set visible), i get following error:
/groups/administrators Not Found You seem to have stumbled upon a page that does not exist. Return to the home page.
Here's query from database: http://paste.kde.org/pyoyy68xj/1hvqu0
Any ideas how to fix this?