It seems that Mac OS Lion server (10.7.0) may have been released with a broken CUPS configuration. Visiting http://localhost:631/admin would generate an “Internal server error”, this seems to be addressed in newer builds (my Macbook Pro which was install from a 10.7.2 image does not exhibit the problem yet a customers server which came bundled with 10.7.0 (upgraded to 10.7.1 > 10.7.2) does).
To resolve the issue
sudo cupsctl --debug-logging
Then switch off the debug logging with
sudo cupsctl --no-debug-logging
I suspect the problem is due to a missing directory because comparing the default, previous & current revisions of the
/etc/cups/cupsd.conf did not show anything that could cause problems.
I’d also go far as to say that you don’t need to turn on debug logging in-order to resolve this issue, it can be any of the options that can be set via
cupsctl as it checks the configuration of the system, this is just a theory as I was unable to dig further because I was on a production system. Resetting the printing system did not solve the issue when attempted previously.