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Topic: Windows 7 Unknown Device FIXED (Read 119435 times) previous topic - next topic


May 06, 2012, 07:59 pm Last Edit: Feb 24, 2014, 09:39 pm by Coding Badly Reason: 1
If your computer doesn't recognize your Arduino and won't install the proper drivers, this fix may work. I used it for my Arduino UNO with Windows 7 64-bit, so steps may vary for other devices and operating systems. I'm writing this from memory so sorry if there are some gaps.

1) Go to the "Unknown device" which is the Arduino.
2) Click around in the "Hardware" tab to open a window with the "Update Driver" button on it. Click it.
3) Choose the option to find the driver from a list on your computer. Then choose "Let me pick from a list of device drivers on my computer".
4) Scroll down and choose "Ports".
5) Choose "Arduino LLC" and then "Arduino UNO". If there is no "Arduino LLC" option, follow the steps below:
  a) Click the "Have Disk" button.
  b) Point to the Arduino folder, then to the "drivers" folder, then select the .inf file for your particular device (In my case it was Arduino UNO.inf).
6) Install the driver. Ignore any warning messages about verification of publication.
7) The Arduino should now be listed as a COM port instead of an unknown device. In the IDE click Tools > Serial Port and select the new COM port. In my case it was COM5.


I give these people full credit for the solution to this problem:

Tip for those without the LLC option



Thank you. This worked like a charm.


I tried this and many other win 7 fixes, i have win 7 x64 and nothing worked. It showed up as a unknown device and when i try to point to the driver it starts to install but says a driver could not be found. I did about a hundered things and then i did this:

My solution was to move the driver for arduino uno rev 3 to the C:\Windows\inf\  folder. Then uninstall the unknown device unplug it plug it back in adn it took like 5 seconds to intall i was so happy. I only post this because it wasnt on most of the threads like this one it didnt work for me.



Thank you! Tried to get my new UNO R3 working on Linux first and could not. Switched to Win 7 and was very disappointed to hit essentially the same error. Found your post and fixed right away. Thank you. Thank you. Thank you.

Might try to tackle Linux later, too, since this gives me some sort of hint on how to proceed there as well. Thanks again.


worked on 32 bit as well thank you.


Many thanks you are a lifesave, much appreciated help. Jim


Same problem with my new Arduino Yun on Windows 7. Thax for the fix :)


Solved my problem. Really thanks!

Coding Badly

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I had this issue where the driver was not getting recognized.  It turns out it was the USB cable itself.  Make sure the cable is newer and not a USB 1.1 cable.  As soon as I changed the cable it worked fine.

Also, when I tried to "force" the driver with the older cable it would blue screen.  So if you get a blue screen when attempting this chances are it is the cable itself.


Wonderful !!
It took me 2 h to get my Arduino going.
I noticed the "unknown device" but I also have (after manual install) a "Ports&LPT" device - which has Error Code 10.
Now I still have a non working (COM5) port, but also a working COM6 !!

Thank you !!



So I've tried this, and it's still not working. I even tried the "Have Disk" option, and it didn't work. This is the error I'm getting. Please help :c


Thank you! This option of moving the .inf file to Windows\inf really works for me.  :)

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