I got this error when I exported to the board::
Error inside Serial.()
gnu.io.PortInUseException: Unknown Application
at gnu.io.CommPortIdentifier.open(CommPortIdentifier.java:354)
at processing.app.Serial.(Serial.java:127)
at processing.app.Serial.(Serial.java:72)
at processing.app.Uploader.flushSerialBuffer(Uploader.java:67)
at processing.app.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:69)
at processing.app.Sketch.upload(Sketch.java:1699)
at processing.app.Sketch.exportApplet(Sketch.java:1761)
at processing.app.Editor$42.run(Editor.java:1955)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
java.lang.NullPointerException
at processing.app.Serial.setDTR(Serial.java:480)
at processing.app.Uploader.flushSerialBuffer(Uploader.java:76)
at processing.app.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:69)
at processing.app.Sketch.upload(Sketch.java:1699)
at processing.app.Sketch.exportApplet(Sketch.java:1761)
at processing.app.Editor$42.run(Editor.java:1955)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
What can this mean?