ok, to len tak pre istotu, takze to bude nejakym configom

toto som naisel :

I finally managed to figure this out. By searching the web, I found a thread detailing a similar problem at the Mozillazine forum. The problem was identified as a missing browser.sessionstore.enabled setting, so I went looking for it in about:config and could not find it. After creating the entry, setting it to true and restarting Firefox, the Restore/Recently functions started working again. Apparently, some bookmark- and session-focussed plugins can cause this problem, but in my case, it must have been something else, as I have never had any such plugins installed.

If you have this problem, here's a detailed walkthrough of how I fixed it. Considering that there seem to be several problems that can cause the Restore/Recently functions to stop working, this is not a guaranteed fix, but it's one more thing to try, at least.

Open a new tab or window.
Type about:config into the address box and hit Enter.
Read the notice and promise to be careful.
Copy this: browser.sessionstore.enabled -- and paste it into about:config's Search box. Hit Enter.
If you copied the text above right, the setting should appear in the list. If it does not, you have the same problem I did. (I would suggest double-checking that you copy/pasted the indicated text and only that text before proceeding.)
If the setting does not exist, right-click the settings list and choose New-->Boolean. Paste the setting name you copied previously into the Name box, hit OK and then set the Boolean value to True. Once you've hit OK, restart Firefox and (hopefully) things should be working properly again.


Thanks to everyone who have offered help and thoughts!
https://support.mozilla.org/en-US/questions/984786