We have a 3400 in a lab, so it doesn't have a configuration on it that we care about. When I tried to upgrade the 9.4 code on it to 11.4 it said:
WARNING: Package junos-11.4R7.5-domestic is not compatible with this hardware.
WARNING: Please install a package with version 7.4 or higher.
I think this means we need to upgrade in steps, which sound too tedious, and I can't find any 9.6 code anyway. I'm wondering if I can boot into the loader, upgrade directly to 11.4, then upgrade the boot loader. Or is there something else that the 9.4 > 9.6 > 10.4 > 11.4 process does to the box?