upgrade without losing bookmarks and tabs, rtc., and NO second device for sync

i posted a response a few minutes ago. but perhaps there was a server error and wasted my time in writing details for you. however, in short, i suggest you create a system restore in windows. you can also backup your bookmarks by exporting them to html file. then you can import them into the new browser, if needed. also, there is some good info at the below for your good question: [[https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles|Back up and restore information in Firefox profiles]]