If you are using organic groups (the og module) (used by openatrium 2) and using >= 7.x-2.0 and >= 7.x-2.12 then you must upgrade to 7.x-2.14 (recommended) or optionally upgrade to 7.x-3.0-beta1.
7.x-2.0-beta3 and 7.x-2.0-beta4 were not affected so you can keep using those versions, or upgrade to 7.x-2.14 (recommended).