After upgrading to puppetdb 2.0.0, my setup seemed broken and I got Notice: Unable to connect to puppetdb server (puppet.koewacht.net:8081):  Not Found
errors. This was due an old puppetdb mosule (1.2.1) is used to install puppetdb. It did work with every 1.x version of puppetdb, but is broken since 2.0.0.
Puppetdb_conn_validator[puppetdb_conn] seems to use a v1 call to check if puppetdb is accessible.
A simple note telleing people that puppetdb needs at least the puppetdb module version 3.x will help avoid this.
affected page : http://docs.puppetlabs.com/puppetdb/2.0/upgrade.html#upgrading-with-the-puppetdb-module