I just updated to 1.9.4 for my server and built a very simple (no events, only a command class) plugin against it. The result is that the server simply shuts down as soon as it finished loading. Debug messages show that my plugin is not even doing anything at all at this point. As soon as the loading messages for the spawn area appears, the "stopping server" message pops up, and the server shuts down normally. This is only happening with this one very simple plugin, which is built against the server jar, has no errors, and worked perfectly in 1.9.3. Edit: disregard this, apparently java simply decided the entire spigot directory is read-only. Thanks java.