The temporary solution is to clear your browser cache when this happen- or specifically just the webpage that isn't loading correctly. Modern browsers keep temporary information about websites in order to load faster, remember auto-fill, passwords, etc. Clearing cache resets this memory and creates a new session like you've never been there before and reloads fresh.

You can do this simply by hitting Ctrl and F5 on your keyboard  when the error page comes up when visiting QB online webpage. This is a common keyboard shortcut which will will clear the cache for whatever webpage you are trying to view.

Something is wrong with QB's web coding and this error keeps happening to a lot of users, me included.