Finally it was possible to conduct upgrade to macOS Sierra .12.6 from version minus three, painful journey. Safari works worser than before Sierra: Not possible to open web page upon entering url into address & search bar (actually it is possible for short time after os reboot, short web surfing session then it turns to problems). Safari under administrator account is not affected. Problem sounds like this: user enters full url or simplified address into address & search bar. Safari's only reaction is the put address text gets centred in address & search bar, that's all. Web page does not open, nor Safari gives any signs it was doing anything to load the page. One can resolve by pushing the reload symbol, address & search bar right side. Long time I didn't not got even this reload/stop loading symbols in address & search bar. I have tested with all extensions removed - no help, therefore those are back now. I have tested also practically all combinations of settings in search preferences - no help. Safari restart does not help. What also help's is to drag url from address & search bar to desktop, close then open Safari, drag icon from desktop back to address & search bar. Any idea how to resolve it? Browsing history I have generated with Safari since twenty fourteen while working yet under os x 10.9 is also gone with upgrade to Sierra - that history was for my work worth of gold enabling high level of productivity. Have backup of history files (~/Library/Safari) - amongst others History.plist - whose size is appx 22MB however to restore from these backups does not help too. Any idea how to resolve this too?