I seem to have this error when I boot my late 2012 iMac running Mavericks GM2. This screen is the first of two such screen I see to log in and appears before the boot sequence... I think it is the "whole disk encryption" decrypt screen, but might be wrong with that for a start. Basically, I have to put my password in here, then it begins to boot (with the apple symbol) then the "user login selector" screen appears with my regular username. I would like to fix this error shown in the image which says "update needed" but really don't know how to google for help as keywords are very generic... Any bright ideas here? Thanks!