[10:38:48] [Netty Server IO #1/ERROR]: Error encoding packet
java.lang.NullPointerException: Cannot invoke "net.minecraft.util.math.BlockPos.func_218275_a()" because "p_179255_1_" is null
        at net.minecraft.network.PacketBuffer.func_179255_a(PacketBuffer.java:168) ~[?:?]
        at net.minecraft.network.datasync.DataSerializers$12.func_187160_a(DataSerializers.java:189) ~[?:?]
        at net.minecraft.network.datasync.DataSerializers$12.func_187160_a(DataSerializers.java:187) ~[?:?]
        at net.minecraft.network.datasync.EntityDataManager.func_187220_a(EntityDataManager.java:209) ~[?:?]
        at net.minecraft.network.datasync.EntityDataManager.func_187229_a(EntityDataManager.java:153) ~[?:?]
        at net.minecraft.network.play.server.SEntityMetadataPacket.func_148840_b(SourceFile:37) ~[?:?]
        at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:38) ~[?:?]
        at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:12) ~[?:?]
        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.invokeWrite(AbstractChannelHandlerContext.java:730) ~[server-1.16.5-20210115.111550-extra.jar:?]
        at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816) ~[server-1.16.5-20210115.111550-extra.jar:?]
        at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723) ~[server-1.16.5-20210115.111550-extra.jar:?]
        at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:111) ~[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:208) ~[?:?]
        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.nio.NioEventLoop.run(NioEventLoop.java:465) [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:832) [?:?]


也不知道是什么问题，求助

把服务器地图备份，删除原来的所有地图文件，重新启动服务器生成一个新的世界，我怀疑是世界方块生成错误

你可以试一下单机能不能打开存档，如果不行就是存档错误
如果可以进入单机就试一下先用单机打开存档再导入服务器