Error "Board at COM4 is not available" when I click on serial monitor.

Hi All,
I am using Lenovo Z500 laptop with Windows 8.1 single langauage 64 bit operating system. When I click on serial monitor, I get a message “Board at COM4 is not available”

Tried google and other instructions on the net but it did not help.

M. Moghe

Arduino Com port Error.doc (121 KB)



You should right click to My Computer, choose Device Manger and expanding item Ports to check the correct Arduino com port. Like below picture the Arduino com port is COM4. After that in Arduino software, choose that com port (COM4) in menu bar Tools → Serial Port.

million thanks friends for quick help, I dont get this option of ports (COM&LTP) in my device manager.


Please find screen shots of Device manager as well as Auduino tools, there are no com ports option.

Serial port missing for Arduino Mega.doc (263 KB)


Please find pdf screenshot of error

Ardino com port error.pdf (97.9 KB)

I am not able to paste in line. I did print screen Ctrl C Ctrl v, etc etc to paste in the message itself.

Can anybody help here.


Nothing showing in ports is usually a driver not installed error or a USB type error.

is it a REAL Mega or a Chinese clone with a CH340 which needs its own driver (google CH340) ?

Have you tried different USB cable and ports or even a different computer ?

Some Arduinos also don't work well with USB 3.0 which your laptop has.
A possible fix for that is to use a USB 2.0 self powered hub attached to the USB 3.0 port.


Dear All,

Thanks for all your Kind help. The solution I choose was, to chuck the Chinese made Arduino and bought a genuine Arduino, this solved all my problems.

Thanks to all :slight_smile:

Mahendra Moghe

Hi guys I've been doing some work on a Infer Red project & I've check to see whether or not I'm on the right port or not (And I am.). I it helps helps These are my error messages

WARNING: Spurious .github folder in 'MFRC522' library
Multiple libraries were found for "IRremote.h"

Sketch uses 9,962 bytes (32%) of program storage space. Maximum is 30,720 bytes.
Global variables use 429 bytes (20%) of dynamic memory, leaving 1,619 bytes for local variables. Maximum is 2,048 bytes.
avrdude: ser_open(): can't open device "\.\COM31": The system cannot find the file specified.

Problem uploading to board. See for suggestions.

Cheers Tim Tam