Press the Alt or F10 key to bring up the toolbar. Then History > Restore previous Session

You may have corrupt sessionstore [v56] sessionstore.jsonlz4 file(s). Delete all sessionstore* files and the sessionstore-backups folder.

Don't delete the files if you need to rescue any data from them, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html

Type about:support<enter> in the address box.

Under Troubleshooting Information on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show or Open Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Locate the above file. Then rename or delete it. Restart Firefox.

What I do.

1. On the first page ('General') of Settings, I select the option at the top "Open previous windows and tabs". 2. I leave the window(s) and tabs open when I quit using the Quit command in the menu.

I am able to delete browsing history before I quit, the window(s) and tabs from the previous session open when I start Firefox again.

Did you follow the instructions I posted?