There is no option to keep Firefox open when you close the last tab, closing the last tab will close Firefox.

Please update to Firefox 41, 39 (which you are running) is old and out of date. Update Firefox to the latest release

You can set this pref to false on the about:config page:

• browser.tabs.closeWindowWithLastTab

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Tyler Downer said

There is no option to keep Firefox open when you close the last tab, closing the last tab will close Firefox.

Confirm.

If you set browser.tabs.closeWindowWithLastTab to false, firefox reopen the last tab, stays with one tab open..... can't close last tab (from X in the right of the tab i mean)

EDIT : If you set browser.tabs.closeWindowWithLastTab to false, firefox reopen the home page...stays with one tab open(the home tab page)..... can't close last tab (from X in the right of the tab i mean), bug report ?

thank you

I have the opposite problem == I want closing the last tab to close FireFox (it uses a LOT of RAM), but now I get a screen showing other recent pages, so I have to click the red X at the top to close the program.

How do I restore the original behavior?

Hi oldmaven

What is the value of browser.tabs.closeWindowWithLastTab if you check that on the about:config page?

Start Firefox in Safe Mode to check if one of the extensions (3-bar Menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: 3-bar Menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes