I have this problem where this will pop up and no one can join and if i leave this message will appear and repeat itself:
[10:30:00] [Netty Epoll Server IO #2/WARN]: An exception was thrown by a user handler’s exceptionCaught() method while handling the following exception: java.lang.NullPointerException at net.minecraft.server.v1_11_R1.NetworkManager.close(NetworkManager.java:247) ~[spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at net.minecraft.server.v1_11_R1.NetworkManager.channelInactive(NetworkManager.java:106) ~[spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:228) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:228) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.handler.timeout.ReadTimeoutHandler.channelInactive(ReadTimeoutHandler.java:144) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:769) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.AbstractChannel$AbstractUnsafe$5.run(AbstractChannel.java:567) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:380) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:268) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116) [spigotmc-1.11.2-R0.1.jar:git-Spigot-3fb9445-6e3cec8] at java.lang.Thread.run(Thread.java:745) [?:1.8.0_112]