Some of my worlds can no longer be played on a server, The root of the issue seems to be saved into the world file, if that helps.
Whenever connecting to the server, all the client and server spit out is "End of stream".
I can create a new world, then run and connect to that just fine, using the same server and configuration. I have also tried this using outdated servers and all servers since 1.5, but the issue remains.
I have tried deleting all the server files, excluding the world folder, and moving the world folder into what I know is a functioning server, but the issue remains.
Attached is world file of one of my examples of the issue I have.
Note: they run fine in single player, and I have tried running them in single player, saving, then reloading in the server, and it still fails to run.