Favicon no aparece

Suddenly I found answer here

You should add "?" to your favicon path and it works! Even with path such as images/favicon.ico. Just try:

<link rel="icon" href="/images/favicon.ico?" type="image/x-icon">

Other browsers works too.

Remember to restart mozilla, because of it's own cache, that is not connected with css and other caching.

updated:

Another way is set redirect from favicon.ico to /images/favicon.ico (301 works)
SamuraiR4cc00n