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What is this that I can't get rid of when I open a new tab? //// http://www.undefined.com/?uid=undefined&uc=undefined&ap=undefined&source=undefined&page=newta

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  • 12 have this problem
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  • Last reply by cor-el

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Some kind of "bug" doesn't want me to use your browser! Any ideas how to get rid of it, as, it doesn't occur with any other browser?

Chosen solution

With Firefox 41 (and higher), it's no longer possible to customize the page shown in a new tab via changing the preference browser.newtab.url in about.config. Because of the fact that hijackers abused the preference in the past, Mozilla decided to remove it (see bug 1118285). Fortunately, by removing it, Mozilla also introduced a new API to bring this functionality back to life as an add-on. This add-on allows the user to choose a certain page in a new tab.

New Tab Override (browser.newtab.url replacement) https://addons.mozilla.org/en-US/firefox/addon/new-tab-override/

This is also available using Classic Theme Restorer (Customize Australis) {web link} Restore squared tabs, appmenu, add-ons bar, small button view and more on Australis UI (Windows/MacOSX/Linux + Fx 29+).

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Chosen Solution

With Firefox 41 (and higher), it's no longer possible to customize the page shown in a new tab via changing the preference browser.newtab.url in about.config. Because of the fact that hijackers abused the preference in the past, Mozilla decided to remove it (see bug 1118285). Fortunately, by removing it, Mozilla also introduced a new API to bring this functionality back to life as an add-on. This add-on allows the user to choose a certain page in a new tab.

New Tab Override (browser.newtab.url replacement) https://addons.mozilla.org/en-US/firefox/addon/new-tab-override/

This is also available using Classic Theme Restorer (Customize Australis) {web link} Restore squared tabs, appmenu, add-ons bar, small button view and more on Australis UI (Windows/MacOSX/Linux + Fx 29+).

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I have this same problem on a friend's computer. All this time I thought it was a browser homepage hijacker.

This solution is hidden on page 6 of the Google results, way past dozens of trendy, arty businesses called 'Undefined'.

Anyway, using the plain Options UI ('about:preferences') won't keep a custom homepage setting either, it goes back to undefined.com, which is why I thought it was a hijacker.

So you have to install an add-on to customise the homepage???

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Hi MartyvH

If you get a new tab like http://undefined.com/ then that is likely caused by an installed extension or possibly malware. The new tab page would normally be the built-in about:newtab page and only an extension or theme could change that.

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

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

See also: