What is a 404 error? Basically it means that the page does not exist. There are two possibilities and one is that you typed in the URL and made a mistake. However, URLs are too long and complicated to remember these days and no-one types them in.
You might enter a domain name, which is a short name like rawinfopages.com, but not a page URL.
The most likely reason why you get a 404 error when browsing the web is because the page on the website was either deleted or moved and has a different URL.
404 Error File Not Found
The page you are looking for might have been removed,
had its name changed, or is temporarily unavailable.
Firefox fixes this by using the Internet Archive Wayback Machine. This website stores copies of web pages on websites and it has recorded nearly half a trillion of them, which is pretty amazing. Whenever a web page changes, a new version is stored by the Wayback Machine, so you can see how websites change over time.
(This is a fun activity all on its own. Want to know what this website looked like way back in June 2014? Here is the RAW Computing home page! Compare it to today's.)
When Firefox encounters a 404 message - page not found - it goes to the Wayback Machine and searches for the page. If a copy is found in the database, then Firefox displays the page. It's genius!
Wayback Machine does not store every page on every website, ever. That would take some doing, but with 498 billion pages stored, there is a good chance that the one that you are looking for that has gone missing is in its database.
If you want to try out this new feature in Firefox you must download and install the latest version of the browser.
Then open it and go to testpilot.firefox.com and get the Test Pilot add-on.
Let us know how you get on with this new feature. Has it worked for your? Leave a comment below.