With Windows 10, can't open any Bluetooth virtual com ports

Bluetooth virtual com port not openable in Windows 10. Last worked in 8.1.

Symptom:
I am an application developer and have tried my application on two computers I just upgraded to Windows 10 (an Acer W510 tablet [formerly win 8.1] and a Dell Precision M6600 [formerly win 7]).

Our devices use a serial port (SPP) service on Bluetooth.  Windows automatically creates the serial ports when pairing the devices.  The devices pair well and the necessary virtual serial ports are created.  They all look great but on both computers, no software is able to open the serial port.

(I must say:  I do like Windows 10 even though I have already seen a "blue screen".)

tried:

- my commercial software

- a test application written in Visual Studio Express 2013

- a test application written in Delphi

- terminal software that would open a serial port and talk with the device

the serial port connection can't be opened due to an error  1168 (ERROR_NOT_FOUND) in CreateFile( ).

As I said, this affects both machines that I upgraded to the official release of Windows 10.

POSSIBLE CAUSES:
Security/permissions? Turned off UAC (user account control); still doesn’t work. User account is Administrator. Tried a new Administrator account (possible account corruption?): no improvement.

Might this be part of a new “windows store” expectation where applications must declare the operating system features they intent to use? This would be a little bit strange since it allowed pairing/unpairing with code. Change to application manifest?

Security/firewall? Turned off firewall; still doesn’t work.

Is the radio off as some kind of power-saving feature? Having trouble determining whether this is the case. One would think that if one attempted to open such a serial port, it would turn on the radio as needed. tried also a laptop not having built-in bluetooth (really!); using external BT dongle, see BT module indicator is blinking (suggesting it is powered-up and operational).

Add something to the application manifest?

Is the com port busy? shouldn't be.  besides, then it should say that the port is in use or “access denied”.

Any “allow windows to turn off the device to save power” features are turned off on relevant devices.  no improvement.

Acer W510 Device manager shows some motherboard features (nothing to do with USB/bluetooth or our devices) that may not have suitable device drivers. the Dell laptop has no Device Manager issues (but has the same inability to use the virtual com port) suggests that these driver issues are not "the" problem.

“Allow Bluetooth devices to find this PC” is not helpful.

“Bluetooth Smart”, “Bluetooth Smart Ready” feature may be implicated in this but don't know enough about them.

using "Developer mode" provided no insight.

using compatibility mode was no help either.

starting to think maybe the driver provided by Windows is not compatible with the Bluetooth hardware in the device.

other people experiencing this problem:  can you leave a comment here about any of your findings?