RS232 problem after Windows 10 update


a week ago an update of Windows 10 was installed on my Notebook. Since then, I have problems running virtual COM ports on the Notebook.

In the attachment the COM port for the Arduino board is shown (without any reported problems) as COM5 in the device manager.

Starting the Arduino IDE and trying to select the indicated COM port I’m facing a surprise. COM5 is not available!? Checked that with IDE 1.8.7 and 1.8.9 - no difference. The available and visible COM ports are used for Ethernet-RS232-converters. But the one for the Arduino is not selectable because it is not shown.

In the meantime I found out, that all my USB to RS232 converters are showing the same strange behavior; visible in the device manager but not available for selection in the application.

Has someone an idea what went wrong and how to solve that Problem? Thanks in Advance.

Why do you say “virtual com ports” ?
If you are running VM’s then COM ports can be an issue depending on the VM software you use and on occasion may need to be re-applied.

Have you at any time manually changed the COM port numbers ?
Your pic could indicate that aspect.

Also if you can identify the particular update that seemed to do it you could roll just that one back ?
Not uncommon for MS to issue an update that also requires an update because the first update breaks something.



Thanks for your response.

I always call COM ports which are not given as "real" hardware of a pc as virtual COM ports (like those connected via USB). I'm open for any other term which explains that difference.

I'm not running a VM.

I never changed the COM port numbers manually. The arduino IDE installation with device drivers assigned it to COM5. In the meantime I changed it to COM6, but same behaviour. It is not shown in the COM port list of the arduino IDE.

I thought about a roll back of the updates, but at the moment only as last chance because I want to keep updates as they help to improve security (at least I hope so).


Thanks for the additional info and it makes sense to call them Virtual ports but we prefer to just stick with com ports.

Not all MS updates are security updates so some can be rolled back when they conflict.
A little over a year ago MS issued a USB update that crippled some hardware including Arduinos.
The answer at that time for most was to roll that update back or revert to the hardware's original driver (non MS)

USB 3.0 can and has also in the past caused issues. The common fix for that was to insert a powered USB 2.0 hub between the Arduino and the computer or use a USB 2.0 port only if your computer has one (not all newer hardware still have USB 2.0)

Where possible any hardware driver updates should be from the hardware supplier and NOT MS.

I also think there was another post about a "notebook" also having new issues with COM ports.
Proper "laptops" seem to be better in that aspect as notebook hardware inc CPU type can on rare occasions be a factor.


Finally the problem was solved by a complete new installation of windows 10 pro and all of the used applications. Don't know why, but Microsoft and hate are always coming up in my mind together.

Glad you got it figured out.