Player data cleared after switching to 14w10b

FIXED IT:
Stop your server
remove all the data from the player directory if there is
copy all the data from the playerdata folder to the player folder
rename everything like this
abcdabcdabcdabcdabcdabcdabcdabcd
to
abcdabcd-abcd-abcd-abcd-abcdabcdabcd

start server
tataaa fixed it

It's every time the server restarts. I will try to figure out that work around, but my skills are very rusty. Thank you, aronvw.

@karst if you know everything better, (betterknower #dutch lol) write a simple program that does this for you.

@aronvw thanks man, I will try that workaround and maybe write a bash script for it.

That work around does not work. it just moves the dat with the dashes inserted to yet another directory "unknownplayers", and recreates a fresh new version in "players" folder.

Hello, I found out how to go back to the last snapshot!

First you have to clear the player folder. After that you run a previous snapshot.

Go to the player data folder.
You need to use the userdata file to know which name which number has!
Rename the file with the username of the player. (My username is Stef_Heck, according to the userdata file my number as example 4321abcdef1234fedcba. I search the folder for that number. Then I rename it to Stef_Heck.dat.)
Repeat this for every player.

After that you move all player data folder files to the player folder, and then you launch your server!

I hope I helped with you guys out! I will go on playing on working snapshots! Next time I back up my world!

Regards Stef Heck.

Bu the way I'm using Time Machine on my Mac to back up, but I forgot to connect my external hard drive to my computer....

I would also like to note that newly created player information also Wipes on a server start/stop.

Meaning if you decide to "just deal with losing all your prior stuff and start new". You will be sadly disappointed each time the server is rebooted.

#notfun

I can confirm what Joseph Charron said -

That work around does not work. it just moves the dat with the dashes inserted to yet another directory "unknownplayers", and recreates a fresh new version in "players" folder.

welp im rolling back to 08a untill 10c or whenever this issue is resolved, i cant afford to spend time manually changing every users file over either 🙂

From MC-50381:

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.

It will be fixed for the next version, but you will need to restore a backup prior to 14w10* to migrate playerdata again

Thanks Dinnerbone 🙂

Extra hugs to Dinnerbone for acting so promptly! 😃

So, assuming I don't have a backup (because I am lazy and awful)... after the fix, will we be able to just proceed with the losses?

(Also, as an interesting note, has anyone noticed that the animals all still recognize the player?)