Do you mean that you run Firefox in Private Browsing mode?

If that is the case then it is not possible to restore the previous session because no data is stored in the Firefox profile folder.

If there is nothing when you click the history button in the "3-bar" Firefox menu button drop-down list or in the History menu then I'm afraid that the session is lost. "Restore Previous Session" uses the sessionstore.bak file that gets created automatically by renaming an existing sessionstore.js file from the previous session when you start Firefox.

I do not run firefox in private brosing mode. In my Options/Privacy/History i have the following: 'use custom settings for history.'. I have nothing in history.

i also have ticked: 'clear history when firefox closes'.

But what is odd is that when i close firefox from Windows Task Manager via 'end process tree', and then i open firefox up again, all of the tabs are still there, restored. Though if i close it via exit, then the history/previous session is wiped. this is truly annoying.

It is a bad idea to kill Firefox via the Windows Task Manager instead of closing Firefox correctly via the Exit/Quit item in the menu because that prevents Firefox from flushing data stored in memory to disk and you also run the risk of corrupting files.

If you aren't keeping history then you also have to accept that you can't restore a previous session. Clearing the history via "Clear history when Firefox closes" prevails and will make it impossible to restore tabs from the previous session (history includes session data)

i constantly have problems with firefox using too much memory, so i constantly shut it down via 'end process tree' and restart it, whereon the tabs will all pop up again, with much less memory. i obviously do not let them all reload because that'll raise the memory level a lot- so all tabs reload, though i click 'offline' in order to stop the complete reloading of tabs. so i bookmark them, at times, and begin again, frequently. i run through this work-around multiple times a day. it's tedious. this is an imperfect method, though firefox is an imperfect browser that hogs too much memory, and it is woefully corrupted through flash. would turning history on use up more memory?

Did you check your extensions to make sure that they aren't responsible for the memory issue?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes