We ran into this as well on upgrading.
We had to apply this patch https://gist.github.com/mrvdb/7588470 to see the error. After that, the solution was pretty easy.
We ran into this as well on upgrading.
We had to apply this patch https:/ /gist.github. com/mrvdb/ 7588470 to see the error. After that, the solution was pretty easy.