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Should "Show your windows and tabs from last time" option results in all session cookies being kept?

  • 4 replies
  • 1 has this problem
  • Last reply by primerano

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I thought the following option only saved session cookies for the current tabs.

When Firefox starts: Show your windows and tabs from last time

But I have observed that it keeps session cookies for every tab I had opened that day. This basically means that the "Show your windows and tabs from last time" retains all session cookies you have ever had set for perpetuity. They will never be deleted.

Steps... don't use as i don't know what is there

  • I have open in a tab. it sets a session cookie.
  • I have 4 other sites open.
  • I close the tab.
  • I close the browser
  • I assume the cookie is gone
  • I open the browser and the 4 (non tabs reopen
  • I open a new tab and go to
  • I observe the session cookie being sent to

All Replies (4)

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Firefox keeps an undo stack for the last 25 tabs in current Firefox releases (browser.sessionstore.max_tabs_undo, browser.sessionstore.max_windows_undo). I assume that cookies from closed tabs are stored as well to be able to reopen closed tabs.

  • History -> Recently Closed Tabs/Windows
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This feels like a bad idea but it is probably what people who use the "Show your windows and tabs from last time" option want.

It makes life hard for developers who are trying to debug cookie issues and it results in conversations like this one.

"Did you restart your browser?" "Yes" "are you sure?" "Yes!, WTF, i'm not an idiot" .. in developer's head. "i clearly see the session cookie on the wire. this guy is an idiot"

When in fact, Firefox is just doing something that we wouldn't expect.

I would propose that when you restart your browser the undo feature is disabled.

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You can exclude the cookies from being part of session restore.

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I don't have control over other people's settings. This is more of a feature request I guess. If someone closes their browser they would not expect sessions for tabs that we're closed before closing Firefox to be active still.

If it is true that Firefox saves session cookies for recently closed tabs (or undo functionally), I would propose that those cookies be tossed on browser restart.