I upgraded the server to 1.9.1 and logged in fine. I played for a few minutes, then hopped in a minecart in the Nether and got booted out. Upon logging in again, I get (on the client):

Connection Lost
Internal Exception: io.netty.handler.codec.DecoderException: IntArray with size 1 is bigger than allowed 0

On the server, I get:

[05:49:40] [Server thread/INFO]: Player1[/192.168.0.2:63599] logged in with entity id 442 at (16.5, 81.7125, 162.49000000953674)
[05:49:40] [Server thread/INFO]: Player1 joined the game
[05:49:42] [Server thread/INFO]: Player1 lost connection: TranslatableComponent{key='disconnect.genericReason', args=[Internal Exception: java.io.IOException: Error while write(...): Broken pipe], siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}
[05:49:42] [Server thread/INFO]: Player1 left the game