"Com 3 is already in use...

Using Arduino IDE 1.x
1

...Try quitting programs that may be using it "

Basically what i did is connect my usb to printer to the laptop. And a Com3 appeared on my Arduino IDE. But whenever i tried to upload a sample program, it kept displaying the error.

My operating system is windows 8.1
I am using the arduino uno

Here is the error log

Binary sketch size: 1,064 bytes (of a 32,256 byte maximum)
processing.app.SerialException: Serial port 'COM3' already in use. Try quiting any programs that may be using it.
	at processing.app.Serial.<init>(Serial.java:171)
	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:175)
	at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
	at processing.app.Sketch.upload(Sketch.java:1671)
	at processing.app.Sketch.exportApplet(Sketch.java:1627)
	at processing.app.Sketch.exportApplet(Sketch.java:1599)
	at processing.app.Editor$DefaultExportHandler.run(Editor.java:2380)
	at java.lang.Thread.run(Thread.java:619)
processing.app.debug.RunnerException: Serial port 'COM3' already in use. Try quiting any programs that may be using it.
	at processing.app.debug.Uploader.flushSerialBuffer(Uploader.java:101)
	at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:175)
	at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
	at processing.app.Sketch.upload(Sketch.java:1671)
	at processing.app.Sketch.exportApplet(Sketch.java:1627)
	at processing.app.Sketch.exportApplet(Sketch.java:1599)
	at processing.app.Editor$DefaultExportHandler.run(Editor.java:2380)
	at java.lang.Thread.run(Thread.java:619)
2

Need to do this. Just go to device manager check port . try to share ur snap shot of device manager

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Basically what i did is connect my usb to printer to the laptop. And a Com3 appeared on my Arduino IDE. But whenever i tried to upload a sample program, it kept displaying the error.
](http://Basically what i did is connect my usb to printer to the laptop. And a Com3 appeared on my Arduino IDE. But whenever i tried to upload a sample program, it kept displaying the error.)
your using arduino & printer @ same instant???
please clarify you connected printer alone to PC???
To which device ur trying to upload????

Please share screen shot of device manager/

3

It's working now

just a simple solution , i uninstalled the arduino com port at Device manager then plugged it back then redirect it to the arduino/drivers directory to update it.