Chef reporting 1.2.1 is a bug-fix release to address compatability with Chef Server 12.
All versions of the Chef reporting add-on are affected if you have upgraded to Chef Server 12.0.0. If you are running Enterprise Chef 11 you can update to reporting 1.2.1 with no side-effects.
When running with Chef Server 12.0.0 with opscode-reporting < 1.2.1, the opscode-reporting-ctl test command will fail. These errors are not in your reporting service, but caused by some shared libraries used in the tests that have different behaviour with Chef 12.
The latest version of reporting can always be found on the Chef download site.
Follow the upgrade instructions on the Chef Documentation site:
* Reporting Upgrade