sun.awt.Win32GraphicsEnvironment ClassCastException in the logs

Issue

• We started to see the below exception in our logs:

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: sun.java2d.HeadlessGraphicsEnvironment cannot be cast to sun.awt.Win32GraphicsEnvironment
at sun.awt.windows.WToolkit.lambda$displayChanged$2(WToolkit.java:843)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

• What does that mean, is that an issue that could cause problems in our environment?

Environment

• Liferay DXP 7.0+
• Java 8

Resolution

• The exception is caused by a Java 8 bug, which doesn't affect the functionality of Liferay.
• You can either safely ignore it, or try to update your Java to the latest version, or as a workaround, you can disable the -Djava.awt.headless JVM flag if you are not using headless mode in Java.

Additional Information

• Strange severe error in logs caused by a Sun JVM bug
• Getting A sun.java2d.HeadlessGraphicsEnvironment cannot be cast to sun.awt.Win32GraphicsEnvironment Error on Startup