[11:51:03 ERROR]: Could not pass event PlayerCommandPreprocessEvent to boosCooldowns v3.8.4
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:509) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:494) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.PlayerConnection.handleCommand(PlayerConnection.java:1035) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.PlayerConnection.a(PlayerConnection.java:880) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.PacketPlayInChat.a(PacketPlayInChat.java:28) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.PacketPlayInChat.handle(PacketPlayInChat.java:65) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.NetworkManager.a(NetworkManager.java:186) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.ServerConnection.c(ServerConnection.java:81) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.MinecraftServer.v(MinecraftServer.java:734) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:289) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:584) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:490) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
Caused by: java.lang.AbstractMethodError: org.melonbrew.fe.Economy_Fe.has(Lorg/bukkit/OfflinePlayer;D)Z
        at cz.boosik.boosCooldown.BoosPriceManager.has(BoosPriceManager.java:116) ~[?:?]
        at cz.boosik.boosCooldown.BoosCoolDownListener.checkRestrictions(BoosCoolDownListener.java:70) ~[?:?]
        at cz.boosik.boosCooldown.BoosCoolDownListener.onPlayerCommandPreprocess(BoosCoolDownListener.java:246) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_65]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_65]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_65]
        at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_65]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:298) ~[spigot.jar:git-Spigot-1.7.9-R0.2-208-ge0f2e95]
        ... 14 more