Many web links can be re-directed to another address. Sometimes the link is set up that way. Sometimes the original page is no longer available.

If the warn on re-direct option is on, you will be told, and can cancel.

In the address bar, type about:preferences#advanced<enter>. At the upper bar, select General.

Look for Warn me when websites try to redirect or reload the page

Note that the setting in "Options/Preferences > 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.

See also:

• https://support.mozilla.org/kb/settings-network-updates-and-encryption#w_general-tab

• http://kb.mozillazine.org/accessibility.blockautorefresh
• http://kb.mozillazine.org/Accessibility_features_of_Firefox