Could not initialize class javax.imageio.ImageIO

Got fixed for me by adding following JVM option.

JAVA_OPTS="-Djava.awt.headless=true -Dawt.toolkit=sun.awt.HToolkit"

Ok so I fixed this issue =)

1. I removed OpenJDK from Linux distribution and installed Oracle Java 7 > u25 by hand. (Good tutorial: http://de.wikihow.com/Installation-von-Oracle-Java-unter-Ubuntu-Linux)

2. Then I added an ApplicationListener which loads the sunToolkit by hand (because AppContext is always null for some reason)

   @SuppressWarnings("restriction")
   public class ContextConfiguration implements ApplicationListener<ContextRefreshedEvent> {
       @Override
       public void onApplicationEvent(ContextRefreshedEvent arg0) {
           //refresh awt context
           if(AppContext.getAppContext() == null) {
               SunToolkit.createNewAppContext();
           }
       }
   }
   

Thanks at haraldK =)