Can you recover any missing tabs using the History menu? In particular, either:

• "3-bar" menu button > History > Recently Closed Windows
• (menu bar or Alt+S) History > Recently Closed Windows

Are you closing Firefox using the menu? This helps with restoring when there was an extra unwanted window. Either:

• "3-bar" menu button > Exit
• (menu bar or Alt+F) File > Exit

But where are those non-visible windows. If you hold down the "Windows" key and tap the Tab key, then release both, after a short delay Windows should show an overlay of open windows and also show whether you have a second desktop.

-Can you recover any missing tabs using the History menu? In particular, either:

 "3-bar" menu button > History > Recently Closed Windows -

Yes.That's how I've been restoring the tabbed window for the last week.At the same time, several more unnecessary ones were opened. But today, this method opens many windows.But there is no necessary one. And in (Firefox View" ---"Open tabs) the necessary window is there.But there's no way to open it.

-Are you closing Firefox using the menu? This helps with restoring when there was an extra unwanted window. Either:

"3-bar" menu button > Exit 

No.I was covering the window with a cross in the upper right corner.

How can I get rid of unnecessary windows?

What kind of pages are loading in the extra windows? Maybe we can figure out the source of them based on what is in them.

In order to make sure you can recover more closed windows in the future, you can increase the cap from 3 to 6 or more. Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.

(2) In the search box in the page, type or paste browser.sessionstore.max_windows_undo and pause while the list is filtered

(3) Double-click the preference to display an editing field, and change the value to 6 (or more) then press Enter or click the blue check mark button to save the change.

Thank you for your help and responsiveness. Today, when the browser is turned on.Everything magically loaded as it should.This is the window where all the tabs are saved.

All unnecessary windows have disappeared in Firefox View.There is only one window left (where all the necessary tabs are). I don't understand how it all happened...But the problem is gone.

browser.sessionstore.max_windows_undo changed it to 6. I'll be watching.

Can you tell me if you change it to 1, what will save only one, the last window?

Thank you for reporting back. Regarding this:

`browser.sessionstore.max_windows_undo` changed it to 6. I'll be watching. Can you tell me if you change it to 1, what will save only one, the last window?

Firefox will save 1 closed window instead of the usual 3. When you want to restore a closed window, you will only be able to access the one that was closed last. The reason this is risky is if sites open popup or popunder windows and you don't notice them before closing windows you care about.

Thanks