SillyPutty125

Thank you! I was able to fix the problem by uninstalling my 32 bit Java, forcing it to use the 64 bit version. I don't know why it was using the 32 bit version to begin with!

I tested with other computers yesterday. The problem is definitely with running a server on this particular computer (running windows 7). I can't reproduce the problem with a server on another machine. To summarize: I have a machine that cannot host a 1.12.2 minecraft server using forge (no mods), but it can host 1.12.2 vanilla and 1.8.9 forge/vanilla without issue. The error message is "Can't serialize unregistered packet" when attempting to join the server from any machine. The client only sees "Disconnected: Failed to connect to the server." Joining the server always works the first time after server startup, and almost always fails the second time. After failing to join once it always fails every subsequent attempt. Java is up to date, and the server is running the latest recommended build of forge. (forge-1.12.2-14.23.5.2768) The problem persists with firewalls and antivirus disabled. I have port forwarding setup properly, though tests have also be performed on a LAN. Here's a snippet from the server debug.log: [02:14:48] [User Authenticator #2/DEBUG] [com.mojang.authlib.HttpAuthenticationService]: Opening connection to https://sessionserver.mojang.com/session/minecraft/hasJoined?serverId=-51d4d3928be0b8be72f5948347df120e37886337&username=SillyPutty [02:14:48] [User Authenticator #2/DEBUG] [com.mojang.authlib.HttpAuthenticationService]: Reading data from https://sessionserver.mojang.com/session/minecraft/hasJoined?serverId=-51d4d3928be0b8be72f5948347df120e37886337&username=SillyPutty [02:14:48] [User Authenticator #2/DEBUG] [com.mojang.authlib.HttpAuthenticationService]: Successful read, server response was 200 [02:14:48] [User Authenticator #2/DEBUG] [com.mojang.authlib.HttpAuthenticationService]: Response: {"id":"f1dd241ea1c84b5eaede23924d8c2017","name":"SillyPutty","properties":[{"name":"textures","value":"eyJ0aW1lc3RhbXAiOjE1NDI3OTUyODU5MDcsInByb2ZpbGVJZCI6ImYxZGQyNDFlYTFjODRiNWVhZWRlMjM5MjRkOGMyMDE3IiwicHJvZmlsZU5hbWUiOiJTaWxseVB1dHR5IiwidGV4dHVyZXMiOnsiU0tJTiI6eyJ1cmwiOiJodHRwOi8vdGV4dHVyZXMubWluZWNyYWZ0Lm5ldC90ZXh0dXJlLzg4YzU2OTY1YjVkOTQyZDliMmQ2NDdkMDc1NWRiNWJlM2UwNzRjMDE3ZjMyOGEzMTRiOGI0MzIwZTgxOWJjYTEifX19","signature":"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"}]} [02:14:48] [User Authenticator #2/INFO] [net.minecraft.server.network.NetHandlerLoginServer]: UUID of player SillyPutty is f1dd241e-a1c8-4b5e-aede-23924d8c2017 [02:14:48] [Server thread/TRACE] [FML]: Handshake channel activating [02:14:48] [Server thread/DEBUG] [FML]: FMLHandshakeServerState: null->FMLHandshakeServerState$1:START [02:14:48] [Server thread/DEBUG] [FML]: Next: HELLO [02:14:48] [Server thread/DEBUG] [net.minecraft.network.NetworkManager]: Set listener of net.minecraft.network.NetworkManager@5ab9cdf5 to net.minecraftforge.fml.common.network.handshake.NetworkDispatcher$1@1b71594 [02:14:48] [Server thread/DEBUG] [net.minecraft.network.NetworkManager]: Enabled auto read [02:14:48] [Netty Server IO #5/DEBUG] [net.minecraft.network.NetworkManager]: Internal Exception: io.netty.handler.codec.EncoderException: java.io.IOException: Can't serialize unregistered packet io.netty.handler.codec.EncoderException: java.io.IOException: Can't serialize unregistered packet at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:125) ~[MessageToByteEncoder.class:?] at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:801) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:804) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831) ~[AbstractChannelHandlerContext.class:?] at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1032) ~[DefaultChannelPipeline.class:?] at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:296) ~[AbstractChannel.class:?] at net.minecraft.network.NetworkManager$4.run(NetworkManager.java:245) [gw$4.class:?] at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) [AbstractEventExecutor.class:?] at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403) [SingleThreadEventExecutor.class:?] at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:442) [NioEventLoop.class:?] at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) [SingleThreadEventExecutor$5.class:?] at java.lang.Thread.run(Unknown Source) [?:1.8.0_191] Caused by: java.io.IOException: Can't serialize unregistered packet at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:42) ~[ha.class:?] at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:12) ~[ha.class:?] at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107) ~[MessageToByteEncoder.class:?] ... 16 more Does anyone have any ideas on what I should check/try next?

Here's the log from the client side

Here's my log for the server with debugging turned on. I'll get back to you on the debug logs for client side.

I'm behind a router, but I have port forwarding setup (works perfectly for 1.8.9). The problem exists regardless of whether I connect to my router's IP, or my computer's IP (192.168.0.2) Yeah, it's at least somewhat unique to my machine. I had a friend test it out on a different machine/network/account and it worked fine. I can personally test it out on another machine tomorrow.

No mods except for forge. I'm running the server with the following batch file: java -Xms512M -Xmx4096M -d64 -jar forge-1.12.2-14.23.5.2768-universal.jar nogui pause I'll open an issue on GitHub if people are confident I'm not doing something stupid.

Sometimes I'm able to get: when I disconnect after my first connection. I still get the same error when I try to reconnect. Here's the log file Also, I should add that this problem does not exist for vanilla minecraft servers. If I run the "minecraft_server.1.12.2.jar" that comes with the forge executable file, everything works fine. The problem is specific to forge, and it's on the server side. My java is updated, and I can connect to the server on the same computer using my LAN IP address, or from a different computer. I'm just not sure what to try next. EDIT: Here's one more log where I was able to connect twice before it stops letting me in.

I am trying running a server with the recommended build of Forge for 1.12.2, and no mods. It seems to work when I join server for the first time, but after I disconnect I am unable to reconnect. The server outputs the following when I try to reconnect: [Server thread/INFO] [minecraft/NetHandlerPlayServer]: SillyPutty lost connection: Internal Exception: io.netty.handler.codec.EncoderException: java.io.IOException: Can't serialize unregistered packet I can run a server for 1.8.9 with mods without any issues, but can't seem to get this version to work. Any ideas on how I can resolve this issue? Thanks! Forge version: forge-1.12.2-14.23.5.2768 (also tested with 2775) debug.log