I updated my vanilla server to the latest snapshot, and when I joined, I had no items. I knew I had some. It looked like I had freshly spawned.
I expect this to be with the new UUID system. Clearly, my UUID or whatever wasn't recorded and my inventory wasn't stored in that, so I had technically never joined.
Do I need to put the UUID for every player on my server in somewhere or something? Please help.
I spent about 3 hours debugging this issue today on an existing multiplayer world and here's what I found:
All existing player_name.dat files get converted to uuid.dat and placed into the directory *playerdata*. (If the player's account is a legacy account the game fails to authenticate the name and crashes. I had to write a script to separate legacy accounts from mojang accounts.)
When existing users or new users join the game their player.dat is created/recreated with an incorrect uuid appended to the filename. The user can leave and come back and retain their player information, but once the server is restarted minecraft cannot find the player's player.dat file since an incorrect uuid has been appended to the filename. This also affects newly created multiplayer worlds.