Archive for March, 2009

Improving everyone’s favorite feature – address not found

One area of Firefox that could use some improvement are the warnings we give when pages are not found.  These could be network errors, firewall issues, URL typos, etc.  Curtis Bartley has been looking at this issue and documenting progress here, and Jesse Ruderman started a bug with some insightful comments here.

Ideally, a good error page does two things:

  1. Tells you what’s wrong in a way that’s both understandable and diagnosable
  2. Helps you decide what to do next

If I type “www.example.cmm” into Firefox now, here’s what I get:


Internet Explorer, Chrome, and Safari all have slight variations on this page.  IE’s isn’t very useful; it gives easy text but no tools. Safari’s design is very minimal, but it does offer search.  Chrome is cutesy, but also intelligently offers suggestions based on what was typed – the most useful of all three.  All three browsers offer additional information via a link, thus removing the bulk of explanation Firefox currently shows.


So what should Firefox do?

For blatant, common URL typos, I think we should redirect straight to the correct URL. currently goes to, why shouldn’t or URLs themselves are an example of forcing users to behave like machines – rather than the preferable reverse – so why not take a step in the right direction by making them more forgiving? (bug freakin’ 175634)

For the addresses that are not blatant typos for existing pages, there’s a few approaches we could take. User-experience-wise, I would love to be able to do better detection of what the problem is and direct the user towards the likely solution. Rather than presenting the user with questions as we do now, we could give them an answer.  We should aim to provide a consistent UI, but perhaps we could change the text sightly based on what the user inputted and try to find the most helpful suggestion. When there’s a very likely solution, that should be the most obvious next step available.

Here’s four scenarios that would cause a 404 today with text customized to what what the user imputed:


While catching all of these scenarios may not be feasible for now, we could be concentrating harder on giving users tools at a 404, not just a warning. I’d love to hear you feedback on this – especially what would help a tech-saavy person such as yourself when you hit a 404.

Just for fun… spoilers!