The Server crashes when i enter

I'm using Mohist but i dont think the reason of this is for the plugins

java.lang.NullPointerException: Cannot invoke "java.lang.Enum.ordinal()" because "p_179249_1_" is null at net.minecraft.network.PacketBuffer.func_179249_a(PacketBuffer.java:184) ~[?:?] at net.minecraft.network.play.server.STeamsPacket.func_148840_b(SourceFile:106) ~[?:?] at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:40) ~[?:?] at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:14) ~[?:?] at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:801) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1071) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:300) ~[server-1.16.5-20210115.111550-extra.jar:?] at net.minecraft.network.NetworkManager.lambda$sendPacket$5(NetworkManager.java:210) ~[?:?] at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:313) ~[server-1.16.5-20210115.111550-extra.jar:?] at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) ~[server-1.16.5-20210115.111550-extra.jar:?] at java.lang.Thread.run(Thread.java:831) ~[?:?] [21:02:49 WARN]: java.lang.NullPointerException: Cannot invoke "java.lang.Enum.ordinal()" because "p_179249_1_" is null [21:02:49 WARN]: at net.minecraft.network.PacketBuffer.func_179249_a(PacketBuffer.java:184) [21:02:49 WARN]: at net.minecraft.network.play.server.STeamsPacket.func_148840_b(SourceFile:106) [21:02:49 WARN]: at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:40) [21:02:49 WARN]: at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:14) [21:02:49 WARN]: at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107) [21:02:49 WARN]: at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) [21:02:49 WARN]: at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:801) [21:02:49 WARN]: at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) [21:02:49 WARN]: at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) [21:02:49 WARN]: at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831) [21:02:49 WARN]: at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1071) [21:02:49 WARN]: at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:300) [21:02:49 WARN]: at net.minecraft.network.NetworkManager.lambda$sendPacket$5(NetworkManager.java:210) [21:02:49 WARN]: at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) [21:02:49 WARN]: at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) [21:02:49 WARN]: at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:313) [21:02:49 WARN]: at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) [21:02:49 WARN]: at java.base/java.lang.Thread.run(Thread.java:831) [21:02:51 INFO]: BreezeDev lost connection: Internal Exception: io.netty.handler.codec.EncoderException: java.lang.NullPointerException: Cannot invoke "java.lang.Enum.ordinal()" because "p_179249_1_" is null