This thing bothers my server for a long time. I still don't know what could possibly cause this issue. Hope any of you here smarter than me can help my find the culprit.
I'll post the crash report under, if there's anything else you need, I'll post upon request.
 

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 19-12-11 下午6:16
Description: Exception getting block type in world

java.lang.NullPointerException: Exception getting block type in world
    at net.minecraft.world.gen.ChunkProviderServer.func_73154_d(ChunkProviderServer.java:314)
    at net.minecraft.world.World.func_72964_e(World.java:751)
    at net.minecraft.world.World.func_147439_a(World.java:677)
    at net.minecraft.block.BlockGrass.func_149674_a(BlockGrass.java:77)
    at net.minecraft.world.WorldServer.func_147456_g(WorldServer.java:569)
    at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:288)
    at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:931)
    at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:431)
    at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:809)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:669)
    at java.lang.Thread.run(Unknown Source)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
    at net.minecraft.world.gen.ChunkProviderServer.func_73154_d(ChunkProviderServer.java:314)
    at net.minecraft.world.World.func_72964_e(World.java:751)

-- Requested block coordinates --
Details:
    Found chunk: true
    Location: World: (-183,54,160), Chunk: (at 9,3,0 in -12,10; contains blocks -192,0,160 to -177,255,175), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Stacktrace:
    at net.minecraft.world.World.func_147439_a(World.java:677)
    at net.minecraft.block.BlockGrass.func_149674_a(BlockGrass.java:77)
    at net.minecraft.world.WorldServer.func_147456_g(WorldServer.java:569)
    at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:288)

-- Affected level --
Details:
    Level name: world
    All players: 2 total; [EntityPlayerMP['xi_la_nai'/468191, l='world', x=909.74, y=41.50, z=231.77](xi_la_nai at 909.7406993221408,41.5,231.77345211942998), EntityPlayerMP['benzhu'/753351, l='world', x=-654.09, y=50.00, z=121.05](benzhu at -654.0857398205269,50.0,121.05339298195648)]
    Chunk stats: ServerChunkCache: 1071 Drop: 0
    Level seed: 16
    Level generator: ID 01 - flat, ver 0. Features enabled: true
    Level generator options: 
    Level spawn location: World: (882,38,436), Chunk: (at 2,2,4 in 55,27; contains blocks 880,0,432 to 895,255,447), Region: (1,0; contains chunks 32,0 to 63,31, blocks 512,0,0 to 1023,255,511)
    Level time: 4338789580 game time, 658092836 day time
    Level dimension: 0
    Level storage version: 0x04ABD - Anvil
    Level weather: Rain time: 129106 (now: false), thunder time: 1824 (now: true)
    Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
    at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:931)
    at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:431)
    at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:809)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:669)
    at java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
    Minecraft Version: 1.7.10
    KCauldron Version: pw.prok:KCauldron:1.7.10-1614.200 Official
    Plugins: CleanroomGenerator, EnderCrystalSpawnerTool, GroupManager, PlaceholderAPI, PluginManager, TuxTwoLib, FireworkBuilder, ConsoleCommands, Lockette, ConsoleSpamFix, PowerNBT, SkinsRestorer, NoBookBug, RedstoneJukeboxTrig, VoxelSniper, DeathMessages, GiftCode, FishLimitPlugin, LagMonitor, FireworkShowManager, ItemRestrict, CoreProtect, dynmap, Itemizer, Essentials, ClearLag, TimingsPatcher, AutoMessage, ManaPlugin, WorldBorder, ProtocolLib, MCCore, AutoSaveWorld, FastAsyncWorldEdit, EssentialsChat, Vault, bugfix, Lores, ScriptBlock, VariableTriggers, QuickShop, TagAPI, SkillAPI, EssentialsProtect, EssentialsGeoIP, EssentialsAntiBuild, RemoteController, RandomLocation, BossShop, EssentialsSpawn, DeathControl, WorldEdit, PlotMe, CrazyCore, ColorMOTD, Multiverse-Core, CrazyLogin, VanishNoPacket, VTTimerPlus, Plan, SimplePrefix, AncientGates, WorldGuard, ItemLoreStats, Multiverse-Inventories, WeatherMan, Transporter, CrazyLogin_Encryptor_xAuth, AreaShop, RPG_Items, Dynmap-WorldGuard
    Disabled Plugins: 
    Operating System: Windows Server 2016 (amd64) version 10.0
    Java Version: 1.8.0_202, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 1945270816 bytes (1855 MB) / 4410896384 bytes (4206 MB) up to 34246361088 bytes (32659 MB)
    JVM Flags: 2 total; -Xincgc -Xmx32767M
    AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
    IntCache: cache: 7, tcache: 0, allocated: 13, tallocated: 95
    FML: MCP v9.05 FML v7.10.99.99 Minecraft Forge 10.13.4.1614 79 mods loaded, 79 mods active
    States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
    UCHIJAAAA    mcp{9.05} [Minecraft Coder Pack] (minecraft.jar) 
    UCHIJAAAA    FML{7.10.99.99} [Forge Mod Loader] (KCauldron-1.7.10-1614.200.jar) 
    UCHIJAAAA    Forge{10.13.4.1614} [Minecraft Forge] (KCauldron-1.7.10-1614.200.jar) 
    UCHIJAAAA    kimagine{0.2} [KImagine] (minecraft.jar) 
    UCHIJAAAA    CodeChickenCore{1.0.7.47} [CodeChicken Core] (minecraft.jar) 
    UCHIJAAAA    ImmibisMicroblocks{59.1.2} [Immibis's Microblocks] ([Build]immibis-microblocks-59.1.2.jar) 
    UCHIJAAAA    cuchaz.ships.core{1.7.10-1.0.3} [Ships Mod Core] (minecraft.jar) 
    UCHIJAAAA    GollumCoreLib{2.0.0} [Gollum Core Lib] ([API]GollumCoreLib-2.0.0-1.7.10.jar) 
    UCHIJAAAA    SlimevoidLib{2.0.4.7} [Slimevoid Library] ([API]SlimevoidLibrary-2.0.4.7.jar) 
    UCHIJAAAA    ateliercanvas{0.2.0} [Atelier Canvas] ([Build]AtelierCanvas[1.7.10]-0.2.0.jar) 
    UCHIJAAAA    Backpack{2.0.1} [Backpack] ([Build]backpack-2.0.1-1.7.x.jar) 
    UCHIJAAAA    BambooMod{Minecraft@MC_VERSION@ var@VERSION@} [BambooMod] ([Build]Bamboo-2.6.8.5.jar) 
    UCHIJAAAA    BiblioCraft{1.11.7} [BiblioCraft] ([Build]BiblioCraft[v1.11.7][MC1.7.10].jar) 
    UCHIJAAAA    Railcraft{9.12.2.0} [Railcraft] ([Build]Railcraft_1.7.10-9.12.2.0.jar) 
    UCHIJAAAA    ForgeMultipart{1.2.0.347} [Forge Multipart] (ForgeMultipart-1.7.10-1.2.0.347-universal.jar) 
    UCHIJAAAA    chisel{2.9.5.11} [Chisel] ([Build]Chisel-2.9.5.11.jar) 
    UCHIJAAAA    CarpentersBlocks{3.3.8.1} [Carpenter's Blocks] ([Build]Carpenter's Blocks v3.3.8.1 - MC 1.7.10.jar) 
    UCHIJAAAA    ChestTransporter{2.0.6} [Chest Transporter] ([Build]ChestTransporter-1.7.10-2.0.6.jar) 
    UCHIJAAAA    chinacraft{0.4.206} [ChinaCraft] ([Build]ChinaCraft-1.7.10-0.4.206.jar) 
    UCHIJAAAA    creativecore{1.3.14} [CreativeCore] ([Build]CreativeCore v1.3.24 mc1.7.10.jar) 
    UCHIJAAAA    customnpcs{1.7.10d} [CustomNpcs] ([Build]CustomNPCs_1.7.10d.jar) 
    UCHIJAAAA    CustomStuff2{0.11.29} [Custom Stuff 2] ([Build]CustomStuff2-0.11.29-MC1.7.10.jar) 
    UCHIJAAAA    CustomStuff3{0.7.10} [Custom Stuff 3] ([Build]CustomStuff3-0.7.10-MC1.7.10.jar) 
    UCHIJAAAA    DynamicTransport{0.1.2.0} [Dynamic Transport] ([Build]DynamicTransport-0.1.2.0-hammer354-a1.jar) 
    UCHIJAAAA    mod_301{0.1} [mod_301] ([Build]ElectricRailway(MC幻想乡、喵玉技术专供) 0.2 for 1.7.10.jar) 
    UCHIJAAAA    flansmod{4.10.0} [Flan's Mod] ([Build]Flans Mod Plus-1.7.10-4.10.0-1.0.3 (1).jar) 
    UCHIJAAAA    MapWriter{2.1.1} [MapWriter] ([Build]Flans Mod Plus-1.7.10-4.10.0-1.0.3 (1).jar) 
    UCHIJAAAA    ForgottenNature{1.7.19} [Forgotten Nature] ([Build]ForgottenNature_1.7.19.jar) 
    UCHIJAAAA    GardenContainers{1.7.10-1.7.0} [Garden Containers] ([Build]GardenStuff-1.7.10-1.7.0.jar) 
    UCHIJAAAA    GardenCore{1.7.10-1.7.0} [Garden Core] ([Build]GardenStuff-1.7.10-1.7.0.jar) 
    UCHIJAAAA    GardenStuff{1.7.10-1.7.0} [Garden Stuff] ([Build]GardenStuff-1.7.10-1.7.0.jar) 
    UCHIJAAAA    GardenTrees{1.7.10-1.7.0} [Garden Trees] ([Build]GardenStuff-1.7.10-1.7.0.jar) 
    UCHIJAAAA    GregsLighting{1.11.2} [Greg's Lighting] ([Build]GregsLighting-1.11.2-mc1.7.10.jar) 
    UCHIJAAAA    mimgMoreBlocks{0.0.1} [mimg's More blocks] ([Build]hxxMoreBlocks.jar) 
    UCHIJAAAA    ImmibisCore{59.1.4} [Immibis Core] ([Build]immibis-core-59.1.4.jar) 
    UCHIJAAAA    mod_Invasion{1.1.5} [Invasion] ([Build]Invasion_1.1.5_1.7.10.jar) 
    UCHIJAAAA    JammyFurniture{5.0.0 [Build Smeagol]} [Jammy Furniture Mod] ([Build]JammyFurniture-5.0.0-1.7.10.jar) 
    UCHIJAAAA    minepainter{0.3.4f2} [MinePainter] ([Build]minepainter-0.3.4f2.jar) 
    UCHIJAAAA    MoarSigns{1.2.4} [MoarSigns] ([Build]MoarSigns-1.7.10-1.2.4.jar) 
    UCHIJAAAA    MorePistons{2.0.0} [More Pistons] ([Build]MorePistons-2.0.0-1.7.10.jar) 
    UCHIJAAAA    cfm{3.4.8} [?9MrCrayfish's Furniture Mod] ([Build]MrCrayfishFurnitureModv3.4.8(1.7.10).jar) 
    UCHIJAAAA    opframe{0.1} [OnlinePictureFrame] ([Build]OnlinePicFrame v1.0 mc1.7.10.jar) 
    UCHIJAAAA    RedLogic{59.1.13} [RedLogic] ([Build]redlogic-59.1.13.jar) 
    UCHIJAAAA    cuchaz.cuchazinteractive{1.7.10-1.0} [Cuchaz Interactive] ([Build]shipsMod-v1.7.10-1.0.4.jar) 
    UCHIJAAAA    cuchaz.ships{1.7.10-1.0.3} [Ships Mod] ([Build]shipsMod-v1.7.10-1.0.4.jar) 
    UCHIJAAAA    signpic{2.8.0} [SignPicture] ([Build]SignPicture-1.7.10-2.8.0-universal.jar) 
    UCHIJAAAA    touhou_alice_core{1.7.10-kog3} [Alice's Core MOD] ([Build]TouhouAliceDoll_kog3.zip) 
    UCHIJAAAA    touhou_alice_dolls{1.7.10-kog3} [Alice's Dolls MOD] ([Build]TouhouAliceDoll_kog3.zip) 
    UCHIJAAAA    touhou_alice_extras{1.7.10-kog3} [Alice's Dolls Ex] ([Build]TouhouAliceDoll_kog3.zip) 
    UCHIJAAAA    tc{4.3.3_011} [Traincraft] ([Build]Traincraft-4.3.3_011.jar) 
    UCHIJAAAA    Tubestuff{59.0.4} [Tubestuff] ([Build]tubestuff-59.0.4.jar) 
    UCHIJAAAA    vending{1.2.3} [vending] ([Build]vending-1.7.10-1.2.3.jar) 
    UCHIJAAAA    mw{1.11.7.7} [Modern Warfare] ([Build]Vic's Modern Warfare-1.7.10-1.11.7.jar) 
    UCHIJAAAA    weaponmod{v1.14.3} [Balkon's WeaponMod] ([Build]weaponmod-1.14.3.jar) 
    UCHIJAAAA    WR-CBE|Core{1.4.1.11} [WR-CBE Core] ([Build]WR-CBE-1.7.10-1.4.1.11-universal.jar) 
    UCHIJAAAA    WR-CBE|Addons{1.4.1.11} [WR-CBE Addons] ([Build]WR-CBE-1.7.10-1.4.1.11-universal.jar) 
    UCHIJAAAA    WR-CBE|Logic{1.4.1.11} [WR-CBE Logic] ([Build]WR-CBE-1.7.10-1.4.1.11-universal.jar) 
    UCHIJAAAA    Dynmap{2.2-143} [Dynmap] ([Func]Dynmap-2.2-forge-1.7.10.jar) 
    UCHIJAAAA    NBTEdit{1.7.2.2} [In-game NBTEdit] ([Func]NBTEdit_1.7.10.jar) 
    UCHIJAAAA    worldedit{6.1.1} [WorldEdit] ([Func]worldedit-forge-mc1.7.10-6.1.1-dist.jar) 
    UCHIJAAAA    armourersWorkshop{1.7.10-0.48.3} [Armourer's Workshop] (Armourers-Workshop-1.7.10-0.48.3.jar) 
    UCHIJAAAA    Gift{1.0.0} [Gift] (CS2_Gift) 
    UCHIJAAAA    MakaiProject{1.0.0} [MakaiProject] (CS2_MakaiProject) 
    UCHIJAAAA    MidAut{1.0.0} [MidAut] (CS2_MidAut) 
    UCHIJAAAA    TouhouBarrage{1.0.0} [TouhouBarrage] (CS2_TouhouBarrage) 
    UCHIJAAAA    TouhouBattle{1.0.0} [TouhouBattle] (CS2_TouhouBattle) 
    UCHIJAAAA    TouhouCraft{1.0.0} [TouhouCraft] (CS2_TouhouCraft) 
    UCHIJAAAA    TouhouFarm{1.0.0} [TouhouFarm] (CS2_TouhouFarm) 
    UCHIJAAAA    TouhouFood{1.0.0} [TouhouFood] (CS2_TouhouFood) 
    UCHIJAAAA    TouhouFZA{1.0.0} [TouhouFZA] (CS2_TouhouFZA) 
    UCHIJAAAA    TouhouFZGift{1.0.0} [TouhouFZGift] (CS2_TouhouFZGift) 
    UCHIJAAAA    TouhouFZN{1.0.0} [TouhouFZN] (CS2_TouhouFZN) 
    UCHIJAAAA    WoolCraft{1.0.0} [WoolCraft] (CS2_WoolCraft) 
    UCHIJAAAA    NyaSamaElectricity{0.6} [NyaSama Electricity] (NyaSamaCompletePack-MCG-181117.jar) 
    UCHIJAAAA    NyaSamaOptics{0.2} [NyaSama Optics] (NyaSamaCompletePack-MCG-181117.jar) 
    UCHIJAAAA    NyaSamaRailway{1.0} [NyaSama Railway] (NyaSamaCompletePack-MCG-181117.jar) 
    UCHIJAAAA    NyaSamaTelecom{0.2} [NyaSama Telecom] (NyaSamaCompletePack-MCG-181117.jar) 
    UCHIJAAAA    ForgeMicroblock{1.2.0.347} [Forge Microblocks] (ForgeMultipart-1.7.10-1.2.0.347-universal.jar) 
    UCHIJAAAA    McMultipart{1.2.0.347} [Minecraft Multipart Plugin] (ForgeMultipart-1.7.10-1.2.0.347-universal.jar) 
    Chisel: Errors like "[FML]: Unable to lookup ..." are NOT the cause of this crash. You can safely ignore these errors. And update forge while you're at it.
    Profiler Position: N/A (disabled)
    Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
    Player Count: 2 / 45; [EntityPlayerMP['xi_la_nai'/468191, l='world', x=909.74, y=41.50, z=231.77](xi_la_nai at 909.7406993221408,41.5,231.77345211942998), EntityPlayerMP['benzhu'/753351, l='world', x=-654.09, y=50.00, z=121.05](benzhu at -654.0857398205269,50.0,121.05339298195648)]
    Is Modded: Definitely; Server brand changed to 'kcauldron,cauldron,craftbukkit,mcpc,fml,forge'
    Type: Dedicated Server (map_server.txt)

1.7.10 is no longer supported on these forums due to how old it is. You will need to update to a more modern version (1.12.2+) to receive support here.