Essentials isn't working?

So, I'm trying to resurrect my dead server. Make it a KitPvP one. But, essentials appears to hate me. I've tried re-installing, but that still doesn't work. Here is what I get from chat when I join the game:
http://imgur.com/uu8loof

And I get this from the console:

02.08 18:25:21 [Server] INFO Enabling Essentials vPre2.14.1.3
02.08 18:25:21 [Server] INFO Bukkit version format changed. Version not checked.
02.08 18:25:21 [Server] INFO git-Spigot-d97e08b-5e85956 (MC: 1.8.8)
02.08 18:25:21 [Server] INFO 1.8.8-R0.1-SNAPSHOT
02.08 18:25:21 [Server] ERROR java.lang.NoSuchMethodError: com.google.common.cache.CacheBuilder.maximumSize(I)Lcom/google/common/cache/CacheBuilder;
02.08 18:25:21 [Server] WARN Essentials userMap not initialized
02.08 18:25:22 [Server] ERROR Error occurred while enabling Essentials vPre2.14.1.3 (Is it up to date?)

Thanks for your help!