You can go from one LTS to the next LTS, and only to the next release from non-LTS releases. So, from 10.10, you would need to go through 11.04, 11.10, then 12.04. If you were coming from 9.10, you could go to 10.04 and then directly from there to 12.04. It all depends on which is more work for you - fussing with multiple upgrade steps, or fussing with getting your data off and back on again. - Tony