The 2 ways so far in this thread to make it work are downgrading to Firefox 19.x or lower, or make a site specific override of the browser version. If Firefox tells E1 it is 19 instead of 20, then E1 will accept it. Like downgrading, this requires action on each of the clients. Both of these are maintenance nightmare.
A third method, and far better one for those of us with more than a handful of end users I think, is to modify the JAS server's browscap.ini. I added the following to my browscap.ini in the PY environment and bounced the PY instance. So far it seems to be working fine. Assuming further testing doesn't discover any new problems, I'll add it to my PD environment tonight when I can kick the users off for a few minutes.
Added the following to JAS server browscap.ini:
<font class="small">Code:</font><hr /><pre>;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; MOZILLA FIREFOX 20.0
[MOZILLA FIREFOX 20.0]
parent=MOZILLA FIREFOX 10.0
version=20.0
majorver=20
minorver=0
[*(X11*) Gecko/* Firefox/2?.*]
parent=MOZILLA FIREFOX 20.0
platform=Linux
[*(Mac*) Gecko/* Firefox/2?.*]
parent=MOZILLA FIREFOX 20.0
platform=Mac
[*(Win*) Gecko/* Firefox/2?.*]
parent=MOZILLA FIREFOX 20.0
platform=Win </pre><hr />