On Firefox 45 there is error: document.querySelectorAll().forEach is not a function.

A simple polyfill fix is:

[code]
(function(){function I(O,p){if(p=Object.getPrototypeOf(O))p.forEach||(p.forEach=[].forEach)}try{I(document.querySelectorAll("body"));I(document.getElementsByClassName("site"))}catch(E){console&&console.error(E)}})();
[/code]

I've added it in class.WpdiscuzCore.php in frontendFiles function, but it was overwritten in next wpdiscuz upgrade, so I had to block upgrades temporarily...

Another problem in this version of Firefox is with padding:2% on input fields in /wp-content/plugins/wpdiscuz/themes/default/style.css?ver=7.3.19, which makes them completely unusable, because it calculates 2% from page height, and text has few pixels at center of line hiding all input...

And just a side-note, that bubble updates are very bad idea on web-site with 10000+ daily readers, it is not fast (on that server with slow database it was cca 1 second server-time per request) and it collapsed our server, when the wp-json request has been unblocked by provider... I already switched that off (removed in script and disabled in configuration) three weeks ago, but until this day multiple tens of users have opened pages from May and still bomb our server with /wp-json/wpdiscuz/v1/update? requests... I had to add filter at start of main index.php to reply them with fast 400... (so for now there is no more problem with that)