When traveling to the end (for the first time), I get the following error in multiplayer:

Internal Exception: io.netty.handler.codec.DecoderException: java.io.IOException: Packet 0/38 (jn) was larger than I expected, found 24576 bytes extra whilst reading packet 38

The problem only happens when I go through an end portal. After it happens, connecting as the same user repeats the error. I tried restarting the server, and that didn't help.

I restored to my last backup, and repeated the process. The same error occurred. Looking at my user in NBTExplorer, I see Dimension=1, so presumably I went to the end but something about rendering the end causes the error.