Can you recover that window using the History menu? Either:

If either of these are available, use this first:

• "3-bar" menu button > History > Restore Previous Session
• (menu bar) History > Restore Previous Session

Next, check:

• "3-bar" menu button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

This problem can occur either when (A) another window was still open -- Firefox will only automatically re-open the remaining window and not the one you closed that had the pinned tabs -- or (B) Firefox is set to delete history when it closes.

For (A):

To avoid that, when you want to close Firefox, use the Exit command on the menu instead of the X button. Either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

For (B):

If your general browsing history is also gone at startup, then you would need to investigate your history settings. More info if needed.

Hi jscher2000, thanks for your reply.

I don't have any option to recover last session but I can recover recently closed windows and, in fact, the pinned tabs are there.

As for your suggestions: - I always make sure that there are no other tabs except the pinned tabs before I close the window and I always use only 1 window at a time. I've found the same as you comment on (A) on this forum but what's weird for me is that I used to close the window normally without having to do all of that. Also note that, as I mentioned on my first post, the pinned tabs are saved normally in my notebook's Firefox after closing the window in a similar way.

- Configuration wise, nothing was touched before this started to happen. Find below my configuration: General > Startup > Open previous windows and tabs is ON Firefox version: 113.0.2 (64-bit) (up to date) Cookies and site data > Delete cookies and site data when Firefox is closed is OFF History > Firefox will REMEMBER HISTORY

With all of these, pinned tabs should be saved after closing and opening a new window.

Regards!

The window-left-open problem mostly seems to affect users with multiple displays. You can check the Windows Task Manager (Ctrl+Shift+Esc), Details tab, to make sure that Firefox really quit after you closed the last visible window -- all firefox.exe processes should close within 30-60 seconds. If you see any remaining, there may be a hidden window, which sometimes is suspicious, and in any case indicates that Firefox never really closed.

Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox Title bar, especially if you have multiple windows or Private Browsing windows open to prevent losing tabs in unnoticed windows.

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit

Hey! Thanks both for the help. As jscher2000 pointed out, there were a dozen processes which remained running after closing Firefox. I decided to take the drastic path and reinstall Firefox, which happened to fix the issue :) Thanks again for your time! Have a nice day!