Firebug Error “Failed to load source for:”

Dec 01, 2010

A while back when I tried to edit a stylesheet in Firebug I got an error that said “Failed to load source for:” followed by the URL of the stylsheet I was trying to edit. After a long while, I finally figured out the problem. Firebug does not follow redirects, so if your stylesheet URL redirects to another URL, you will most likely get that message. This was a huge pain for about a day until I realized that I could “live” edit the stylesheet in the same way with the Web Developer Firefox Add-on. In this case, we had setup a canonical domain redirect that redirected all non www traffic to wwww. The stylesheet was being called from the non www URL, thus Firebug wouldn’t let me edit it. Problem solved!