The website should be providing an alternate url in this case. It might be that you are accessing the site from an old url. Would it be possible to clear the cache of the site or to try to search for the new url in a private browsing window.

If it is the browser, is there any add ons or changed features that might be preventing the redirect? Try Safe Mode:

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

Web servers can send 301 (moved permanently) and 302 (moved temporarily) codes to Firefox, and normally Firefox will automatically redirect to the new address. Something in your Firefox or on your system seems to be blocking redirects.

You can check the HTTP response headers with the Live Http Headers extension to see if there is a location header present.

• https://addons.mozilla.org/firefox/addon/live-http-headers/

You can also check this setting:

• Firefox > Options > Advanced > General : Accessibility :
  [ ] "Warn me when web sites try to redirect or reload the page"

The setting in "Options > Advanced > General" is meant as an accessibility feature, as you can see by the label of that section, so that people with disabilities or people who use screen readers do not get confused and is not meant as a safety protection to stop redirecting.

With that said for redirect in Firefox the feature to disable is here:

• Try Firefox Button → Options → |Advanced| → Accessibility →[ ] Warn me when Websites try to redirect or reload the page
• Troubleshoot Firefox issues caused by malware