@leocg I close Opera every night before I shut down my computer. That seems normal to me. The popup then says something like "You're closing X tabs, are you sure? Don't worry, they'll be restored...". Then Opera closes...that window. Generally this all goes well. However, sometime you find there is still another window open. You may have forgotten, but in my case I never knew it was there (like when opened by some website). Then all your tabs are lost. Until recently you could then remove the last tabs and sessions file and you were safe. This does not work anymore. Since this unknown or unaware window is the last one you used, as far as I know, your closed tabs are also gone (hard to test, for if the test fails your tabs are gone). Of course one could be suspicious every day (seems not good for user experience to me) and check whether there's a hidden window still open, but how much effort is it to warn you you're closing your window with many tabs, that you will lose, for there is also a window with only one tab (of a few) still open which (contrary to the reassuring popup text) will mean all your tabs are lost? Over the years I've seen multiple posts here of people losing hundreds of tabs this way. Why does Opera offer all kinds of user-friendliness and convenience, like storing passwords, but in this case tells us to be disciplined? But if possible I'll check the option you mention. I now use history but that only keeps record for three months.