I'll give some context after getting to the point. I have a saved %AppData%\Mozilla\Firefox\Profiles\SOME_LETTERS_AND_NUMBERS.default\sessionstore-backups\previous.js (includes Windows environment variable) which I'd like its content to replace the current session; I want all the tabs and windows in it to be in Firefox once again. In a session that included some videos (which tend to play when loading, taking both CPU and attention from me to pause/close them) and numerous tabs, FF crashed. I was in a middle of something and wanted to get quickly back to it so I didn't restore my previous session right away. The time-sensitive event ended and I wanted to recover the session but menu > History > Restore Previous Session was disabled. I hurried to get some information and found out where the session were located and copied the directory content as soon as I could. The 3 other files in the folder were not related to the session I wanted (file in 1st paragraph). I tried to restore the session but when I loaded it didn't show what normally is shown after a clean FF exit, about:sessionrestore with the windows & tabs tree, but instead had my home page and Restore Previous Session enabled, however when I clicked the latter nothing was restored and the files in the session dir (in 1st paragraph) were replaced so I closed FF, deleted the files, replaced them with the good ones and repeated the process and got the same result (I did that a few times with variations on what files I replaced). Thank you kindly for your help