In 10.1.1 the generated column was called "grid_code", in 10.2 this has been renamed to "gridcode", which according to the specs in the provided url seems right (although no capital 'G').
I didn't find anything in the release notes that mentioned this change.
It did break my program (but was relatively easy to fix).
Hopefully this forum post will help some other people and limit their time debugging this issue.