Robert Fedick

I too am seeing this on my Vanilla world.  The world was generated in 1.14 and upgraded through the 1.15.x's to 1.16 and then 1.16.1  My console dumped this log a few times now.  Each time, the server kept running and a player was able to continue playing.

@Johnibur - I too am working with a world brought from our 1.13.2 server.  We have tried the cache clearing numerous times but the world is now zombie city.  As such we have created a new world in 1.14 and are not seeing the problem.  We are sad.

I have loaded a 1.13.2 world using 1.14 server.jar using the cache clearing method described by the moderator. 

After a few hours or after a restart, the lighting issue is back.  Am I supposed to add

--forceUpgrade --eraseCache

to my java server start command from now on?

This keeps coming back and has made my world unusable.

I run a 1.8.1 SMP world generated clean in 1.8.1, no mods (pure vanilla.) I have a Verizon Fios connection with 75Mbps up and 75Mbps down. I maintain the server on a Windows 7 pro 64 bit system with 4GB of RAM, the latest 64-bit JAVA and proper updates with no other software running on the server.

Several of my users, all with decent internet speeds of their own, have had this happen.
They are either outright disconnected or, mostly, they connect for a few seconds to one minute and are kicked with the io.netty error.

It seems that this happens mostly when the affected player comes near a location in the world where mass production of animals is being done. What I mean is player 1 will have a farm with 200 chickens in a 10x10 block pen and player 2 will approach within 100 blocks or so and then lag so badly that they disconnect. When reconnecting thereafter they get the error.

I have seen a player who experiences this error come into the game for the minute the game allows and then he moves away from the area and can thereafter eliminate the error.

In the other cases, I've deleted the affected player's world\playerdata\player.dat file and they are then able to return to the server (losing all their items).

This problem began to appear in our environment as of 1.8 but I think it has happened to others on previous versions.

My gut feeling is that it is related to sync issues in the io.netty 4.x handler but I am not a programmer.

I hope this description helps a coder who cares. If you have any questions, I'll be monitoring this thread.

I run a Vanilla SMP server on an HP Desktop:
Windows 7 Pro SP1
Java 8_25 (64Bit loaded from java.com offline version)
vanilla 1.8 (never modded or messed with)
4GB RAM
Intel Core2Quad Q8200 (2.33GHz)

This machine is dedicated to this server only and is used only for this purpose.

Internet connection is 75MBs up and down via Fiber.
Server directly connected to Linksys Gigabit router with high priority set to both port 25565 and the MAC address of the server.

Here's the key part of my batch file to start the server:

java.exe -Xmx2048M -Xms2048M -jar minecraft_server.jar nogui

And my Server.properties file is:

#Minecraft server properties
#Mon Oct 27 23:44:44 EDT 2014
generator-settings=
op-permission-level=4
resource-pack-hash=
allow-nether=true
level-name=world
enable-query=false
allow-flight=false
announce-player-achievements=true
server-port=25565
max-world-size=29999984
level-type=DEFAULT
enable-rcon=false
force-gamemode=false
level-seed=
server-ip=
network-compression-threshold=256
max-build-height=256
spawn-npcs=true
white-list=true
spawn-animals=true
snooper-enabled=false
online-mode=true
resource-pack=
pvp=true
difficulty=3
enable-command-block=false
player-idle-timeout=0
gamemode=0
max-players=8
max-tick-time=60000
spawn-monsters=true
view-distance=10
generate-structures=true
spawn-protection=16
motd=Corrupt again!!!! I hate this!! Backup restored AGAIN!

I defrag often, update always, and run diskchecks monthly. I've never experienced any problems running a server in 2 years and 1.8 was the first time I've had these problems.

Problems:
People unable to stay logged into the server. Client get's kicked with IO.Netty errors and their avatar stays in game. Performing 'list' command at console shows user still logged in. I am unable to 'kick' them. If they log in again, a second instance of thier avatar shows and a second user with the same username shows on the list. User is disconnected from the server within a minute or two at most.

I haven't tried deleting the user UUID (which deletes their inventory too, right?) but I have gone back to yesterday's backup and was able to get them back on. That causes us to lose a day's work and I'm losing users because of that.

Someone mentioned they have lots of animals spawned and when other users come near, this happens. That's exactly what happened last night to one of my users when he came near my farm. Lag, lag and then he logged out and back in to try and alleviate the problem but was then 'ghosted' and kicked.

This time there were no errors posted on the console but I have seen many IO.Netty errors thrown when this has happened in the past. I will provide copies of any files any developer needs to help solve this problem. I have kept all logs and world files (including corrupt ones) just in case.

In testing with one affected user: He was able to connect to a second instance of a server (new world, separate port) on the same server with no issues but could not connect to the main server.
When he logged in and saw his ghost, he moved as far from the chunk he was in as possible, this took several login attempts. Once far away from the offending location, he was able to get back on. Whenever he moved back to that chunk, he was dumped from the game and given the netty io error.

Sometimes the server console shows the error, sometimes not.

I am available to send files as requested, I keep copies of everything, logs, world files, etc.

Please, dinnerbone kenobi, you are our only hope.