Board Thread:Bug Reports/@comment-25684944-20150322111448/@comment-25565811-20150327065520

But I assume, you don't start a new world then. That's why you get chunks generated with different versions in one world and these steep drops. It's not a bug just a change of versions, When you generate the whole landscape with the same version, it is smooth.

What you could do, is to remove the old region files and generate them again by travelling the same region. Make a backup before you try. Probably you won't want to do it with regions, you've built in. So these regions will stay old in all cases.