Problem/Bug Continuous server crash

I'm the owner of a private server that I've been running, managing, and upgrading for the past couple months now.

For the last month however, it's been crashing, but it's very inconsistent. Some days it doesn't crash at all, and some days (like today) it crashes multiple times (6 times just this morning). I think it has to do with world corruption, but I have absolutely no idea.

Here's the plugin list:



Here are 4 of the crashes from today (it's always the same):

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Code:

[15:53:02] [Server thread/INFO]: There are 2 out of maximum 24 players online.
[15:53:02] [Server thread/INFO]: Admins: Rayzr522
[15:53:02] [Server thread/INFO]: mod: baconlover511
[15:53:03] [Server thread/INFO]: baconlover511 was slain by Skeleton
[15:53:03] [Server thread/ERROR]: Encountered an unexpected exception
java.lang.NullPointerException
    at net.minecraft.server.v1_8_R3.PersistentCollection.a(PersistentCollection.java:79) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.a(WorldServer.java:963) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.save(WorldServer.java:923) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at org.bukkit.craftbukkit.v1_8_R3.CraftWorld.save(CraftWorld.java:753) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:678) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:556) [spigot.jar:git-Spigot-d97e08b-880a532]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_60]

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Code:

[15:59:08] [Server thread/INFO]: Giving 1 of iron axe to baconlover511.
[15:59:10] [Server thread/INFO]: CONSOLE issued server command: /list 
[15:59:10] [Server thread/INFO]: There are 2 out of maximum 24 players online.
[15:59:10] [Server thread/INFO]: Admins: Rayzr522
[15:59:10] [Server thread/INFO]: mod: baconlover511
[15:59:10] [Server thread/ERROR]: Encountered an unexpected exception
java.lang.NullPointerException
    at net.minecraft.server.v1_8_R3.PersistentCollection.a(PersistentCollection.java:79) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.a(WorldServer.java:963) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.save(WorldServer.java:923) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at org.bukkit.craftbukkit.v1_8_R3.CraftWorld.save(CraftWorld.java:753) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:678) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:556) [spigot.jar:git-Spigot-d97e08b-880a532]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_60]

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Code:

[16:08:05] [Server thread/INFO]: [BitzAPI] Disabling BitzAPI v1.1
[16:08:05] [Server thread/INFO]: [BitzAPI] [BitzAPI] BitzAPI v1.1 has been unloaded!
[16:08:05] [Server thread/INFO]: Saving players
[16:08:05] [Server thread/INFO]: Saving worlds
[16:08:05] [Server thread/INFO]: Saving chunks for level 'Hub'/Overworld
[16:08:05] [Server thread/ERROR]: Exception stopping the server
java.lang.NullPointerException
    at net.minecraft.server.v1_8_R3.PersistentCollection.a(PersistentCollection.java:79) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.a(WorldServer.java:963) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.save(WorldServer.java:923) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.saveChunks(MinecraftServer.java:433) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.stop(MinecraftServer.java:475) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:592) [spigot.jar:git-Spigot-d97e08b-880a532]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_60]

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Code:

[16:14:32] [Server thread/INFO]: [BitzAPI] Disabling BitzAPI v1.1
[16:14:32] [Server thread/INFO]: [BitzAPI] [BitzAPI] BitzAPI v1.1 has been unloaded!
[16:14:32] [Server thread/INFO]: Saving players
[16:14:32] [Server thread/INFO]: Saving worlds
[16:14:32] [Server thread/INFO]: Saving chunks for level 'Hub'/Overworld
[16:14:32] [Server thread/ERROR]: Exception stopping the server
java.lang.NullPointerException
    at net.minecraft.server.v1_8_R3.PersistentCollection.a(PersistentCollection.java:79) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.a(WorldServer.java:963) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.WorldServer.save(WorldServer.java:923) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.saveChunks(MinecraftServer.java:433) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.stop(MinecraftServer.java:475) ~[spigot.jar:git-Spigot-d97e08b-880a532]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:592) [spigot.jar:git-Spigot-d97e08b-880a532]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_60]

However, just now I noticed that the last two crashes happened while I was shutting down the server and right when it tried to save my Hub world. Is that possibly the problem?

Please help! This glitch has deleted inventories more than once, and it's really stressful to continuously deal with it.

I appreciate any advice you can give me.

 

For some reason, after moving to a new panel (because my providers were going to discontinue my old panel), the glitch is gone. I do think it had something to do with the Hub world being corrupted, but I still have the same Hub world, yet no problems.....