I have a RoR app that works fine in 10.2 via mongrel, but obviously with older everything.
It does not get much loving care, so all the gems are out of date (maybe a year out of date).
I just tried to run it on my 10.3 box with new gems (and mongrel). No luck, it dies immediately.
I just took a look at the Ruby Forum to see if there were any upgrade suggestions.
None, in fact the only post I found was saying that the user could not get mongrel to run.
So before I start chasing my tail, does anyone have mongrel/RoR/10.3 working?