Few months ago, we have introduced exception codes which are being collected on this page:

http://projects.theforeman.org/projects/foreman/wiki/ErrorCodes (the list is not complete)

We should refactor our codebase and expose these codes more. They are rarely printed, usually on the debugging console. We should consider printing it in error boxes so we are able to easily find them and point users on mailing lists, IRC and docs directly to resolutions, like:

http://projects.theforeman.org/projects/foreman/wiki/ErrorCodes#ERF51-4505-invalid-path