Server keeps crashing and kicks players out

When I connect to the server, the server then closed by itself and kicks players that had login to the server. This problem started to happen yesterday.
I've just try to connect server again and the problem still exist. Here's the log.
What happened to my server?

[08:14:07] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.server.v1_12_R1.ReportedException: Loading NBT data
at net.minecraft.server.v1_12_R1.NBTTagCompound.a(SourceFile:446) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.NBTTagCompound.load(SourceFile:78) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.NBTCompressedStreamTools.a(SourceFile:119) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.NBTCompressedStreamTools.a(SourceFile:84) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.NBTCompressedStreamTools.a(SourceFile:80) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.RegionFileCache.d(RegionFileCache.java:87) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.ChunkRegionLoader.loadChunk(ChunkRegionLoader.java:55) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at org.bukkit.craftbukkit.v1_12_R1.chunkio.ChunkIOProvider.callStage1(ChunkIOProvider.java:21) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at org.bukkit.craftbukkit.v1_12_R1.chunkio.ChunkIOProvider.callStage1(ChunkIOProvider.java:1) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at org.bukkit.craftbukkit.v1_12_R1.util.AsynchronousExecutor$Task.init(AsynchronousExecutor.java:150) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at org.bukkit.craftbukkit.v1_12_R1.util.AsynchronousExecutor$Task.initAsync(AsynchronousExecutor.java:95) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at org.bukkit.craftbukkit.v1_12_R1.util.AsynchronousExecutor$Task.run(AsynchronousExecutor.java:85) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[?:1.8.0_144]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[?:1.8.0_144]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_144]
Caused by: java.io.UTFDataFormatException: malformed input around byte 6
at java.io.DataInputStream.readUTF(DataInputStream.java:634) ~[?:1.8.0_144]
at java.io.DataInputStream.readUTF(DataInputStream.java:564) ~[?:1.8.0_144]
at net.minecraft.server.v1_12_R1.NBTTagCompound.b(SourceFile:433) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.NBTTagCompound.load(SourceFile:75) ~[minecraft_server.jar:git-Bukkit-fb414fe]
at net.minecraft.server.v1_12_R1.NBTTagCompound.a(SourceFile:440) ~[minecraft_server.jar:git-Bukkit-fb414fe]
... 14 more
[08:14:07] [Server thread/ERROR]: This crash report has been saved to: /aternos/server/./crash-reports/crash-2018-02-27_08.14.07-server.txt
[08:14:07] [Server thread/INFO]: Stopping server
[08:14:07] [Server thread/INFO]: [Essentials] Disabling Essentials v2.0.1-b488
[08:14:07] [Server thread/INFO]: [MyPermissons] Disabling MyPermissons v1.0.0
[08:14:07] [Server thread/INFO]: [MyPermissons] The plugin was disabled!
[08:14:07] [Server thread/INFO]: [HealthBar] Disabling HealthBar v1.8.3
[08:14:07] [Server thread/INFO]: HealthBar disabled, all the health bars have been removed.
[08:14:07] [Server thread/INFO]: [[0;32;22mMyPet[m] [mDisabling MyPet v2.3.3[m
[08:14:08] [Server thread/INFO]: [[0;32;22mMyPet[m] [mCustom entity registry found: net.citizensnpcs.nms.v1_12_R1.util.CustomEntityRegistry[m
[08:14:08] [Server thread/INFO]: [TreeCapitator] Disabling TreeCapitator v1.0
[08:14:08] [Server thread/INFO]: [Sentinel] Disabling Sentinel v1.4.5 (build 155)
[08:14:08] [Server thread/INFO]: [Sentinel] Sentinel unloading...
[08:14:08] [Server thread/INFO]: [Sentinel] Sentinel unloaded!
[08:14:08] [Server thread/INFO]: [Citizens] Disabling Citizens v2.0.22-SNAPSHOT (build 1487)
[08:14:08] [Server thread/INFO]: [SkinsRestorer] Disabling SkinsRestorer v13.3
[08:14:08] [Server thread/INFO]: Saving players
[08:14:08] [Server thread/INFO]: Rei_Ya lost connection: Server closed
[08:14:08] [Server thread/INFO]: Rei_Ya left the game
[08:14:08] [Server thread/INFO]: Saving worlds
[08:14:08] [Server thread/INFO]: Saving chunks for level 'world'/overworld
[08:14:08] [Server thread/INFO]: Saving chunks for level 'world_nether'/the_nether
[08:14:08] [Server thread/INFO]: Saving chunks for level 'world_the_end'/the_end

PS: Only when server owner connect to the server let this situation happen.

I've tried your method but when I go to upload the world that without playerdata, it said that I cannot upload file larger than 200MB, where my file is 500MB. What should I do?

I've deleted other useless data to make it under 200MB. I uploaded the world again and first the problem still exist. And then I try once again the server suddenly works fine. I don't know why as I have do nothing to it.
Here's the log works normally: https://mclo.gs/m7nCs2q

Yes, for now. Strange... I'm curious about the reason why the problem suddenly fixed

Just now, the problem exists again and when I try once more time it fixed by itself. So unstable...

Here's the problem again and the log: https://mclo.gs/vTyp4Ku

I've done what you told but the situation has not change. Here's the log: https://mclo.gs/vw2iY3i
And here's the list of plugins that I have installed: https://ibb.co/m8NVoH
Should I remove them or not? If yes, which should I remove?
I've tried to delete the playerdata and the problem had been solved for one day. On the next day, the problem happened again.
Here's another log: https://mclo.gs/WG0Hcso

Nope... I don't think so. The server always crashes when the owner of the server login. And it seems that the name of the server owner causes the problem as I've tried to login to the server with another account which name is same to the server owner's, Rei_Ya. It then crashed for no reason. Strange

Okay. I've done what you told. I've downloaded the world and delete related player data. Then I zipped the file and uploaded the world. It showed that upload success. But when I entered to the world, I found that it is not the world that I've uploaded. No one was kicked at this time but it was not the world that I want.
My world is 9MB but when I download the world that I uploaded it become 3MB. What's wrong with my world?