I recently went thru the process of upgrading most of my virtual machines from Debian Wheezy to Debian Jessie. One of the changes that affected quite a few things was the upgrade from Apache 2.2 to 2.4. One of the packages that is affected by this change is smokeping. There is a bug filed which documents the workaround process required to get smokeping working under Debian Jessie.

The Debian Jessie Apache 2.4 package uses a /etc/apache2/conf-{available,enabled} directory structure instead of /etc/apache2/conf.d/ for extra configuration files.

An OTRS system I upgraded today was also affected by this change, I had to re-symlink the otrs.conf file in conf-enabled.