In additional contents with the wysiwyg preference set to text, the codemirror initalizes with mode xml. It lints properly but To recreate on main: 1. Set wysiwyg preference to text 2. Go To tools->news 3. Edit or create a news item 4. In your browser console, copy and paste the following in: document.querySelectorAll('.CodeMirror').forEach((cm, i) => { console.log(`Editor ${i}:`, cm.CodeMirror.getMode().name); }); It will return Editor 0: xml It lints html properly, but the mode is wrong. If you go to system preferences and find intranetuserjs and expand the box, then run the same command in your console, you'll get Editor 0: javascript