Nesting <a> inside <button> doesn't work in Firefox

To make it work in all browser, Firefox too you have to change it to

<a href="#"><button class="btn"></button></a>

or as suggested by Billy Moat in case of bootstrap there was no need of <button> you could just do

<a href="#" class="btn">GO</a>

Probably better to just do this:

<a href="#" class="btn">Go!</a>

This issue is happening in FF and IE(< 10). The browser simply doesn't like the tag button when it's used as a link.

Quick solution in bootstrap is to use and give a class of btn btn-default (or your choice of button style).

However, you can use in a form (submit button for instance) and you shouldn't have an issue.