Minecraft "java.security.AccessControlException: access denied"

Some plugins (Such as ExecuteEverywhere) sometimes can require specific java security policies to be set to work with some server software such as KCauldron, it's a simple fix that takes people (including myself) to find just by searching around. Here's the error you might see:

java.security.AccessControlException: access denied ("javax.management.MBeanTrustPermission" "register")

First add the following parameter to your Java startup line for your Minecraft server, if you're using Multicraft, just edit (or ask your host) the .jar.conf configuration startup parameters.

-Djava.security.policy=server.policy

Should look something like:

java -Xmx2G -Xmx2G -Djava.security.policy=server.policy -jar KCauldron.jar nogui

Create a file in your servers base directory named "server.policy" and add the following contents to the file and save it:

grant {
   permission javax.management.MBeanTrustPermission "register";
};

After it's saved start the server (with the above policy parameter) and the server and plugins should start without errors.