Crash at Login on Sever

I have two bugs with my servers since i have updated in 18w21a/b.

When i log in, the connection is lost and I have this message  : 

Internal Exception : io.netty.handler.coded.DecoderException : h: Loading NBT data.

and when i look the log of my server, it shown : 

[14:59:46] [Netty Epoll Server IO #3/ERROR]: io.netty.handler.codec.EncoderException: java.io.UTFDataFormatException: encoded string too long: 69631 bytes

[14:59:00] [File IO Thread/ERROR]: Failed to save chunk
java.io.UTFDataFormatException: encoded string too long: 69631 bytes
	at java.io.DataOutputStream.writeUTF(DataOutputStream.java:364) ~[?:1.8.0_45-internal]
	at java.io.DataOutputStream.writeUTF(DataOutputStream.java:323) ~[?:1.8.0_45-internal]
	at hk.a(SourceFile:33) ~[minecraft_server.18w21b.jar:?]
	at gw.a(SourceFile:433) ~[minecraft_server.18w21b.jar:?]
	at gw.a(SourceFile:64) ~[minecraft_server.18w21b.jar:?]
	at hc.a(SourceFile:48) ~[minecraft_server.18w21b.jar:?]
	at gw.a(SourceFile:433) ~[minecraft_server.18w21b.jar:?]
	at gw.a(SourceFile:64) ~[minecraft_server.18w21b.jar:?]
	at gw.a(SourceFile:433) ~[minecraft_server.18w21b.jar:?]
	at gw.a(SourceFile:64) ~[minecraft_server.18w21b.jar:?]
	at hg.a(SourceFile:104) ~[minecraft_server.18w21b.jar:?]
	at hg.a(SourceFile:92) ~[minecraft_server.18w21b.jar:?]
	at bqt.b(SourceFile:267) ~[minecraft_server.18w21b.jar:?]
	at bqt.a(SourceFile:249) [minecraft_server.18w21b.jar:?]
	at cgr.c(SourceFile:42) [minecraft_server.18w21b.jar:?]
	at cgr.run(SourceFile:35) [minecraft_server.18w21b.jar:?]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_45-internal]

[14:59:46] [Netty Epoll Server IO #3/ERROR]: io.netty.handler.codec.EncoderException: java.io.UTFDataFormatException: encoded string too long: 69631 bytes

I have tried with and without my datapack.

My friend, who play on the server with me, didn't have this bug.