My site is running Piwik 2.13.1. Under Chrome (well, Chromium) 42 the dashboard loads fine, but under Firefox 36 (my preferred browser) I get the following error:

ReferenceError: $ is not defined index.php:68:8
ReferenceError: $ is not defined index.php:739:0
ReferenceError: $ is not defined index.php:764:0

This indicates that jQuery has not loaded properly. Without this library, the dashboard is basically worthless.

Of course, I can get by with Chrome support only, but to fail to load under Firefox seems like a serious issue and I hope it could be addressed.