NullPointerExpection

Error
Loading libraries, please wait...
Failed to start the minecraft server
java.lang.NullPointerException
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:213) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at com.google.common.collect.Lists$ReverseList.(Lists.java:767) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at com.google.common.collect.Lists.reverse(Lists.java:759) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at net.minecraft.server.v1_8_R3.UserCache.b(UserCache.java:191) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at net.minecraft.server.v1_8_R3.UserCache.(UserCache.java:70) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at net.minecraft.server.v1_8_R3.MinecraftServer.(MinecraftServer.java:136) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at net.minecraft.server.v1_8_R3.DedicatedServer.(DedicatedServer.java:43) ~[spigot.jar:git-Spigot-044d928-e8c6403]
at net.minecraft.server.v1_8_R3.MinecraftServer.main(MinecraftServer.java:926) [spigot.jar:git-Spigot-044d928-e8c6403]
at org.bukkit.craftbukkit.Main.main(Main.java:193) [spigot.jar:git-Spigot-044d928-e8c6403]

Cause of Error
Your server storage got full and the usercashe.json file got corrupted.

Solution
Stop the server
Delete the usercashe.json file from your servers FTP file access.
Then start your server.
If this does not work please contact our customer support.