Hi, is this the only data that gets lost, or are settings and add-ons also changing?

Pinned tabs are stored in, and restored from, your session history file. (Pinned Tabs - keep favorite websites open and just a click away)

Problems can occur if...

(1) ...the window with the pinned tabs is not the last closed window when you exit Firefox.

Sometimes users discover a pop-up/pop-under window after closing their window with the pinned tabs. If that happens to you, immediately restore the main window using Ctrl+Shift+N (undo close window) and close the popup first before closing the main window.

Alternately, it is safest to shut down Firefox using the menu. Either:

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

(2) ...history is cleared.

Session history is considered part of history. Firefox can be set to clear history when you close it, and Firefox has features to "forget" history, but probably this does not explain something that happens very intermittently.

Do you have any add-ons that clear your history?

Do you have any cleaning programs like CCleaner or Advanced SystemCare that remove certain browser data?

I really don't know if it cleared any add-ons or not - only thing i notice are the pinned tabs being gone. no cleaning programs - only Malwarebytes and McAfee.

Is there a way to recover the pinned tabs I had?

Thanks for your help.

Could you try restoring recently closed windows? Either:

• "3-bar" menu button > History > Recently Closed Windows
• "Library" toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows
• (Windows) Ctrl+Shift+N

Of course, if Firefox didn't already restore your previous session, then you probably need to do this first:

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