I get this message,
Request Entity Too Large
The requested resource
/index.php
does not allow request data with POST requests, or the amount of data provide
The only thing that would work for me was to tune up the SSL Buffer Size. You can set this by...
...
# Set this to something big...
SSLRenegBufferSize 10486000
...
...and then just restart Apache for the change to take effect. (Found this at: http://forum.joomla.org/viewtopic.php?p=2085574)
You can also use "Location /" to simply apply the setting to a whole VirtualHost:
# ...
SSLRenegBufferSize 101048600
# ...