You have a couple of options to try:
Specify the
-Djava.awt.headless=true
parameter at startup time (either for your app or the server itself in the JVM_ARGS of theServer Start
tab or startWebLogic.sh).Try
export DISPLAY=:0
before starting your weblogic server.Check to see if the X Server is running in another port
Try to completely unset the display before starting the server
unset DISPLAY