When somebody tries to convert a minecraft world made in Beta 1.2 and under, Minecraft can't convert it to the new Anvil World Format. Instead, it will just regen a new world and not convert it at all. This is a problem in Minecraft versions that use the Anvil World Format (Minecraft 1.3, 1.4, 1.5, 1.6)
MC-21842
Can't convert Minecraft Worlds made in Beta 1.2 and down.
Resolved
Duplicate
0
Sal
(Unassigned)
Unconfirmed
anvil, mcregion, world
Minecraft 1.6.2
Retrieved
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.