I confirm the issue in 1.13-pre1 for our survival server as well.
[15:14:15] [Server thread/ERROR]: Encountered an unexpected exception
h: Exception ticking world
at net.minecraft.server.MinecraftServer.w(SourceFile:697) ~[server.jar:?]
at rx.w(SourceFile:365) ~[server.jar:?]
at net.minecraft.server.MinecraftServer.v(SourceFile:626) ~[server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:531) [server.jar:?]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_171]
Caused by: java.lang.StackOverflowError
at bql.a(SourceFile:417) ~[server.jar:?]
at bbi.a(SourceFile:270) ~[server.jar:?]
at bfx.a(SourceFile:225) ~[server.jar:?]
I assume that only the upgrade was fixed, because even in 1.13-pre1 the protection plague is everywhere. Can you confirm that already upgraded servers with 18w22b or 18w22c will still have books full of protection and librarian villagers selling protection all levels. Is there any workaround or only a backup of 18w22a or earlier version is the only solution?
I also confirm the issue. When entering an existing world a server crash occurs.
Edit: Logging with other accounts was possible and now I can also log with my account.
I confirm it for 1.12 too. Dismounting a horse has a chance to make the horse disappeared.
The only workaround is to disconnect from the server and reconnect. The horse is then visible again.
I confirm that the files were 0 bytes. Backup is also affected and it is corrupted. Isn't any way to recover? Can I create those files?