Sorry, this could indicate that Firefox did not install fully. Could you back up your bookmarks before following the rest of my suggestions: * [[Restore bookmarks from backup or move them to another computer]] * ''For safety, also:'' [[Export Firefox bookmarks to an HTML file to back up or transfer bookmarks]] The DMG file contains the Firefox application, but Firefox needs to run from the Applications folder to create permanent data folders. Could you double-check the steps in the following article and make sure Firefox is getting successfully installed: [[How to download and install Firefox on Mac]] Can you get a persistent installation?