The Torbutton startup observer component is sometimes not initialized
The symptoms of the problem is the info message: "While creating services from category 'profile-after-change', could not create service for entry 'StartupObserver', contract ID '@torproject.org/startup-observer;1'" It is quite difficult to reproduce. But the best step I have found so far is clicking on New Identity while loading a page (sounds strange, I know). Then even after closing and restarting Tor Browser the component is not initialized. One can "reset" that behavior surprisingly if one updates an extension (at least updating Torbutton solved the problem for me).