You should be able to close the about:config tab like other tabs. If the button is not visible, try the keyboard shortcut Ctrl+w (close current tab).

If what you were doing in about:config involved changing the URL for new tabs, I wonder whether you might have made a typo and entered about:config instead of about:newtab or about:blank? You could check here:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste newtab and pause while the list is filtered

(3) Double-click the browser.newtab.url preference and enter your preferred page:

• Page thumbnails (default) => about:newtab
• Blank tab => about:blank
• Built-in Firefox home page => about:home
• Any other page => full URL to the page

You did not tell me where to enter the preference ' what is a string value" please

A string value is plain text as opposed to Boolean that take true and false or an Integer pref that takes a number from 0 the 32768 (15 bit signed).

What is the current value of the browser.newtab.url pref and the home page setting?

Did you set either of them to about:config?

You can reset the browser.newtab.url pref via the right-click context menu to the default value.

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

You can check the home page setting:

• Tools > Options > General > Startup: Home page
• https://support.mozilla.org/kb/How+to+set+the+home+page

If you do not keep changes after a restart or otherwise have problems with preferences, see:

• http://kb.mozillazine.org/Preferences_not_saved

Hi Nic, when you type newtab in the search box that appears above the list — just above it, not the regular search box — Firefox will show all the preferences that contain newtab. You should not need to create a new one, just edit the one I listed.

Hello, the about:config is already set as the browser startup homepage

see in cor-el's above reply how to set the home page, Tools > Options > etc....

or

you have to change the browser.startup.homepage from about:config to www.google.com or other web page you want (if you want that choice type or paste from here browser.startup.homepage in the search field, double-click on it, change the homepage to google or other you want, click ok).

thank you