So I'm setting up a server for a project I'm starting (more on that as it develops), following my own instructions (http://old.richarddcrowley.org/blog/view/123). It turns out they're not quite right anymore and I can't figure it out.
I'm getting constant 403 errors even though RewriteLog seems to indicate that my rewrites are happening correctly. The solution is of course to google for the solution, but in most of my searches, my old site is the top result. Uh oh.
But I figured it out thanks to Server Watch forum users. In a nutshell, Ubuntu now forces you to explicitly enable more bits of the Apache proxying system by hand. Thus:
a2enmod proxy a2enmod proxy_balancer a2enmod proxy_http a2enmod proxy_ftp a2enmod proxy_connect