Device is not currently available, access denied


I am having a problem with the Plugable USB to DB-9 RS-232 adapter. I have been using this for several months without issue and now they will not work with my application.

Windows 10, 32-bit
Application calls a script that uses the MODE command to copy a file to the com port

This has been working successfully for months and now I get an error:
Device COM3 is not currently available
Access is Denied

I have checked and there are no other programs accessing the COM port.

I can get it to work if I do the following:
Uninstall the device (from device manager), deleting drivers
Re-install with Profilic drivers
The command works successfully
However, after a reboot, the error will occur again

I have tried driver versions v11, v12 and now v16 with the same results.

I have about 25 of your devices and they have been working fine for months and now at least 20 of them have started exhibiting this behavior.

Please advise how to resolve.


I did run the diagnostic tool. Let me know where to send the zip file.

Dave also contacted us by email and this problem appeared to be caused by an update to Windows Defender that blocked the COM port. Disabling Windows Defender allowed access the port.