Yes... You need to upgrade it to the latest ArubaOS 5.x first. The problem is tha 3.x images have a hard limit on an upgrade image size.. ArubaOS 6.x exceeds that limit, but 5.x is needed so that the AP can upgrade AND change that limit. So you need to first connect those access points to a controller that is running the latest 5.x, then go to 6.x