From MozillaZine Knowledge Base
This preference controls whether to use a pop-up alert or an error page for sites that can't be loaded because of a network problem.
Possible values and their effects
Show an error page for pages that couldn't be loaded. (Default)
Display an alert when a page can't be loaded and remain on the previous page.
- When this preference is set to true, some ad blocking software and techniques can cause IFRAME or Flash ads to show an error page where the ad would be rather than showing nothing in that spot. When this preference is set to false, the same situation may cause an alert.
First checked in
Has an effect in
- Netscape (all versions since 7.0)
- Mozilla Suite (all versions since 1.1 beta)
- Firefox (all versions)
- SeaMonkey (all versions)