My problem stems from two plugins which both use Gson, namely Factions and WorldGuard (custom build from new-ish source). If I have either plugin loaded into CraftBukkit without the other, there's no problem. If I have both of them, WorldGuard loads first with no problem but then Factions fails to load with this error: Code: java.lang.IllegalAccessError: tried to access field com.google.gson.Gson.DEFAULT_ANON_LOCAL_CLASS_EXCLUSION_STRATEGY from class com.google.gson.GsonBuilder at com.google.gson.GsonBuilder.<init>(GsonBuilder.java:93) at com.bukkit.mcteam.factions.entities.EM.<clinit>(EM.java:34) at com.bukkit.mcteam.factions.Factions.onEnable(Factions.java:34) at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:117) <snip> I've tried recompiling both plugins with Gson built in, and recompiling both plugins with Gson as a referenced external library JAR in the manifest file (both pointing to the same file). Also with one using an external Gson library JAR and the other using built-in Gson. All of those combinations failed the same way, with Factions giving the above error. So... as my experience with Java is limited, can anyone with more experience provide advice on how to get around this sort of conflict? I expect the answer is pretty basic and due to my inexperience with Java, but I'm just about stumped.