[20:17:31] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
        at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_301]
        at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_301]
        at net.minecraft.util.Util.func_181617_a(SourceFile:47) [h.class:?]
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:890) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:474) [nz.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:826) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:685) [MinecraftServer.class:?]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_301]
Caused by: java.lang.NullPointerException
        at net.minecraft.block.Block.func_180657_a(Block.java:728) ~[aow.class:?]
        at net.minecraft.server.management.PlayerInteractionManager.func_180237_b(PlayerInteractionManager.java:400) ~[or.class:?]
        at net.minecraft.server.management.PlayerInteractionManager.func_180784_a(PlayerInteractionManager.java:275) ~[or.class:?]
        at net.minecraft.network.NetHandlerPlayServer.func_147345_a(NetHandlerPlayServer.java:1076) ~[pa.class:?]
        at net.minecraft.network.play.client.CPacketPlayerDigging.func_148833_a(SourceFile:40) ~[lp.class:?]
        at net.minecraft.network.play.client.CPacketPlayerDigging.func_148833_a(SourceFile:10) ~[lp.class:?]
        at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13) ~[hv$1.class:?]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_301]
        at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_301]
        at net.minecraft.util.Util.func_181617_a(SourceFile:46) ~[h.class:?]
        ... 5 more


开了这么久服务器，都没问题，刚才重启了一下，就这样了，任何变量都显示不出来

已经自己修完了