This discussion is exactly like the title says. Whenever I gain experience on my server, from any source, my client crashes, and I can’t reconnect with out the same thing happening. I have tried restarting the server, but that does nothing. The only thing that helps is recreating the world. I do not think that this has anything to do with corrupt player data on the world, but am not sure. If this is a known bug, please let me know. Besides that, any help would be a huge appreciated.
Please paste the log of the server and the log of the client(found in the launcher) to Pastebin and post the links here.
Most likely deleting the playerdata file would also fix this problem, as opposed to re creating the entire world
RandomByte, do you need the crash report, or just the log?
NVM, I just remembered that neither of them actually crashed.
Here is the Server Log - http://pastebin.com/uqfG9Zxx
And the Client Log - http://pastebin.com/aY9RaJPs
I hope this is what you need 
Roll back to a previous build, the latest merge hasn’t had it’s things ironed out to the new system.