I've been running a Minecraft server for a while and never had any problems with server upgrades before, up to and including version 1.1. Now I'm testing 1.2.x, and although I always spawn in the location where my home used to be, the world there is completely different. What am I missing?
Resolved. Here's what I did: Copied the 'world' folder from the server folder to single player 'saves' folder. Opened the world from the 'saves' folder in MCEdit. Opened the 'World Info' dialog in MCEdit (Ctrl-I), then ran the 'Repair regions' tool. Saved the world. Ran the most recent Minecraft client, and the world appeared in the world list, but said that it needed to be converted. Opened the world in single player mode from there and it converted, saying 'Converting to Anvil'. Copied the world back to the server folder and ran it in multiplayer mode. Everything was back to normal!