MassiveCore error

[acaB-G]

A moment ago it worked great, but out of nowhere it closed and when I opened the server, this message came out:

[19:50:12 ERROR]: Error occurred while enabling MassiveCore v2.14.0 (Is it up to date?)
java.lang.NullPointerException
at com.massivecraft.massivecore.store.accessor.FieldAccessorSimple.get(FieldAccessorSimple.java:31) ~[?:?]
at com.massivecraft.massivecore.store.accessor.Accessor.copy(Accessor.java:133) ~[?:?]
at com.massivecraft.massivecore.SimpleConfig.load(SimpleConfig.java:82) ~[?:?]
at com.massivecraft.massivecore.MassiveCore.onEnableInner(MassiveCore.java:228) ~[?:?]
at com.massivecraft.massivecore.MassivePlugin.onEnable(MassivePlugin.java:82) ~[?:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321) ~[spigot.jar:git-Spigot-fdc1440-53fac9f]
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:340) [spigot.jar:git-Spigot-fdc1440-53fac9f]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) [spigot.jar:git-Spigot-fdc1440-53fac9f]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:357) [spigot.jar:git-Spigot-fdc1440-53fac9f]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:317) [spigot.jar:git-Spigot-fdc1440-53fac9f]
at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:199) [spigot.jar:git-Spigot-fdc1440-53fac9f]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:524) [spigot.jar:git-Spigot-fdc1440-53fac9f]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]

Uso spigot 1.8.8