Question

When Firefox updated to version 6 recently, a site I’m working on severely broke.

The site operates normally when browsing to any page without a hash tag but if you try to navigate to a page with a hash tag (e.g. #test) or refresh the page once a hash tag was applied, the page refreshes as quickly as it can infinitely.

This is a Asp.Net MVC 2 site created around a year and a half ago.

Answer 1

Turns out, this is an issue with an old version of MicrosoftAjax.js (the one that comes installed with Asp.Net MVC 2).

Open up the MicrosoftAjax.debug.js file and check the file version number. The top of this file will look like this if this is your problem:

 // Name:        MicrosoftAjax.debug.js
 // Assembly:    System.Web.Extensions
 // Version:     4.0.0.0
 // FileVersion: 4.0.20526.0

That’s the version that contains this bug. The latest file version as of this writing is 4.0.30205.0. Upgrade to the latest version and the problem goes away. As mentioned in a comment by Nathan Fox, I got the latest version from the Microsoft cdn and more specifically the minified and debug versions.

For the curious, I traced the problem down in the javascript file.

The buggy version includes:

 if ((Sys.Browser.agent === Sys.Browser.Firefox) && window.location.hash && (!window.frameElement || window.top.location.hash)) {
      window.history.go(0);
 }

Which was corrected to the following in the newer version:

 if ((Sys.Browser.agent === Sys.Browser.Firefox) && window.location.hash && (!window.frameElement || window.top.location.hash)) {
      (Sys.Browser.version < 3.5) ?
      window.history.go(0) :
      location.hash = this.get_stateString();
 }