Firefox 69.0, Windows 7 Pro 64bit I was having problems with Firefox taking a long time (30 seconds?) to fetch an open tab when restarting and I was unable to add or delete bookmarks. I learned about and turned off sync (set identity.fxaccounts.enabled to false) and that seemed to solve the problem. No more startup delay and was able to add and delete bookmarks. But now I've discovered that at some point in the session the ability to add and remove bookmarks disappears. If I close Firefox and restart, I get a message that Firefox is still running. I close the running session, restart, and the ability to add and delete bookmarks reappears, but eventually breaks again. The places database passes validation checks.