In Minecraft SMP 1.0
Placed stronghold in INVALID biome at (4, -70)
Placed stronghold in INVALID biome at (46, 30)
I get this message when server starts. What does it mean? What can I do about it?
This is due to a stronghold being generated in an invalid location, such as under sand. From what I can gather, clearing your player data and running Chunkster (backup first) on your world should fix the problem.