I ran into this issue, and after doing some research I found this thread on the Puppet Users mailing list¹. It does not look like the OP ever filed an issue, and so I am doing so now, since I am having the same issue.

I have a gist with a copy of my puppet.conf, settings.yaml and the error text².

I am using:

Ubuntu 12.04 (32bit, 'server')

foreman 1.1-~nightlybuild13433410 installed from packages (testing the apt packages)
foreman-proxy 1.1-~nightlybuild13433420
puppet 3.0.0-0.1rc3puppetlabs1
puppetmaster 3.0.0-0.1rc3puppetlabs1

[1] https://groups.google.com/d/topic/puppet-users/pYdk5ChOUa4/discussion
[2] https://gist.github.com/3190017