proxy: No protocol handler was valid for the URL
I am using mod_proxy to hide my host-wide Geneweb setup behind a bunch of Apache vhosts. I was surprised to find that after migrating to Apache 2.2 my mod_proxy setup had ceased working. The vhost’s access.log was showing a 403 and the error.log was churning messages containing “proxy: No protocol handler was valid for the URL”. I fed that message to Google and after looking at a few random threads I began to understand that the mod_proxy configuration had most probably changed between Apache 2.0 and Apache 2.2.
In addition to mod_proxy.so additional modules now have to be loaded in order to support a few configuration directives. The mod_proxy configuration for my Geneweb setup is as follow :
ProxyPass /robots.txt http://www.bensaude.org/robots.txt
ProxyPass / http://kivu.grabeuh.com:2317/
ProxyPassReverse / http://kivu.grabeuh.com:2317/
A quick look at the available modules in /etc/apache2/mods-available showed me that in addition to mod_proxy.so I also had mod_proxy_ajp.so, mod_proxy_balancer.so, mod_proxy_connect.so, mod_proxy_ftp.so, mod_proxy_html.so and mod_proxy_http.so. On a hunch I decided that mod_proxy_http.so was the best candidate so I tried that first.
ln -s /etc/apache2/mods-available/proxy_http.load \
via» proxy: No protocol handler was valid for the URL.