[Fix] Ubuntu Error Opening serial port '/dev/ttyACM#'

I've got this error while I was trying to upload my code to arduino MEGA2560 with Ubuntu 12.10 x64

The fix is simple, close all of the Arduino IDE and edit this file(~/root/.arduino/preferences.txt) find serial.debug_rate and change that line into 'serial.debug_rate=9600'

Hope this helps

processing.app.SerialException: Error opening serial port '/dev/ttyACM4'.

at processing.app.Serial.<init>(Serial.java:178)

at processing.app.Serial.<init>(Serial.java:77)

at processing.app.debug.Uploader.flushSerialBuffer(Uploader.java:77)

at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:172)

at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)

at processing.app.Sketch.upload(Sketch.java:1706)

at processing.app.Sketch.exportApplet(Sketch.java:1662)

at processing.app.Sketch.exportApplet(Sketch.java:1634)

at processing.app.Editor$DefaultExportHandler.run(Editor.java:2346)

at java.lang.Thread.run(Thread.java:722)

Caused by: gnu.io.UnsupportedCommOperationException: Invalid Parameter

at gnu.io.RXTXPort.setSerialPortParams(RXTXPort.java:171)

at processing.app.Serial.<init>(Serial.java:163)

... 9 more

processing.app.debug.RunnerException: Error opening serial port '/dev/ttyACM4'.

at processing.app.debug.Uploader.flushSerialBuffer(Uploader.java:101)

at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:172)

at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)

at processing.app.Sketch.upload(Sketch.java:1706)

at processing.app.Sketch.exportApplet(Sketch.java:1662)

at processing.app.Sketch.exportApplet(Sketch.java:1634)

at processing.app.Editor$DefaultExportHandler.run(Editor.java:2346)

at java.lang.Thread.run(Thread.java:722)