Please see the following issues for breaking changes to plugins and themes. https://github.com/NodeBB/NodeBB/issues?utf8=✓&q=is%3Aissue+milestone%3A1.9.0+label%3A"breaking+change+(themes)"+ https://github.com/NodeBB/NodeBB/issues?q=is%3Aissue+milestone%3A1.9.0+label%3A"breaking+change+(plugins)" If you have plugins that are affected, please update your plugin and add the below to your package.json "nbbpm": { "compatibility": "^1.9.0" } to your package.json.