HELP: Exception in thread "main" java.lang.ExceptionInIn...

I need help! I just finished creating my server, I went to start it up, and I got this:

Last login: Fri Apr 11 19:55:46 on ttys000
/Users/xxxxxxxx/Desktop/xxxxxxxxxxxxx\!/start.command ; exit;
xxxx-xxxxx-iMac:~ xxxxxxxx$ /Users/xxxxxxxx/Desktop/xxxxxxxxxxxxx\!/start.command ; exit;
Exception in thread "main" java.lang.ExceptionInInitializerError
at org.apache.logging.log4j.util.PropertiesUtil.<init>(PropertiesUtil.java:71)
at org.apache.logging.log4j.util.PropertiesUtil.<clinit>(PropertiesUtil.java:31)
at org.apache.logging.log4j.status.StatusLogger.<clinit>(StatusLogger.java:48)
at org.apache.logging.log4j.LogManager.<clinit>(LogManager.java:44)
at net.minecraft.server.MinecraftServer.<clinit>(SourceFile:49)
Caused by: java.lang.NullPointerException
at org.apache.logging.log4j.util.ProviderUtil.<clinit>(ProviderUtil.java:70)
... 5 more
logout

[Process completed]

I use a Mac OS X computer. My start.command looks like this:

#!/bin/bash
cd "$(dirname "$0")"
exec java -Xmx700M -Xms700M -jar minecraft_server.jar

WHAT SHOULD I DO?