If your Firefox is set to restore every time, then after you exit out, either: This is nothing unusual in my experience, as it keeps happening about once a month. *) There was no obvious crash, though Firefox just did not automatically load upon restarting my Macbook, which is always running the latest version of any software installed. ) There was no obvious crash, though Firefox just did not automatically load upon restarting my Macbook, which is always running the latest version of any software installed.How can I restore my tabs from that file? However, I cannot find a way to restore the tabs from that file as Firefox just keeps ignoring any changes that I make to the files name and folder contents. While none of the files in that folder are intelligible, I can see from text snippets that a file called 'upgrade.jsonlz4-20191202093317' is the only one that potentially holds a backup of my tabs. Exploring the forum for help, I found that menu 'Help' > 'Troubleshooting Information' will lead to a page on which one can find the profile folder, which in turn contains a folder called 'sessionstore-backup,' in which Firefox keeps a history of previous sessions' tabs. For reasons unbeknownst to me*, Firefox started without restoring the tabs from my previous session.

Restore session firefox manually