Unable to connect USB Bluetooth adapter to Windows 10

Indivara · Oct 22, 2019

After updating to macOS Catalina 10.15, the USB Bluetooth adapter on my Mac fails to connect to a Windows 10 guest. The error says 'Unable to connect {device name} to "Windows 10" now. Try to connect this USB device later'
The help page suggested is the link below, but none of the solutions work.
https://kb.parallels.com/en/10136

Other USB devices connect without any issue.
Parallels Desktop-14.1.3-45485, also tried with the trial version of Parallels 15 but the same problem occurs, so paying for an upgrade is not a solution.

Any idea on how to fix this?
Thanks

JacobJ2 · Oct 24, 2019

I'm also having this problem - it's unfortunate because I really need direct access to a bluetooth adapter in Windows. I'm using a Laird BT820 Bluetooth Dongle. It works fine in the current version of Parallels, but not if macOS Catalina is installed.

DenizC · Oct 25, 2019

I've the same problem with 15.1.0.. Because of that I stopped using Parallels and installed Bootcamp..

JacobJ2 · Oct 25, 2019

I think I've found a workaround for this problem (and don't think it is Parallels that is at fault here). After doing some digging around in Apple's Bluetooth Explorer development tool, I discovered that macOS Catalina is actually attempting to use my external bluetooth adapter/dongle as the Bluetooth host controller for macOS. Because the bluetooth adapter is "in use" by macOS, it can't be mapped to the VM. This did NOT used to be the default behavior for macOS. A little searching around and I found you can instruct macOS to not use external adapters as host controllers by typing the following in terminal.

Code:

sudo nvram bluetoothHostControllerSwitchBehavior=never

After that, restart your system.

After a reboot, I was able to map my Bluetooth adapter to parallels like I used to be able to. Hope that helps you all!

DenizC · Oct 30, 2019

JacobJ2 said:
I think I've found a workaround for this problem (and don't think it is Parallels that is at fault here). After doing some digging around in Apple's Bluetooth Explorer development tool, I discovered that macOS Catalina is actually attempting to use my external bluetooth adapter/dongle as the Bluetooth host controller for macOS. Because the bluetooth adapter is "in use" by macOS, it can't be mapped to the VM. This did NOT used to be the default behavior for macOS. A little searching around and I found you can instruct macOS to not use external adapters as host controllers by typing the following in terminal.

Code:

sudo nvram bluetoothHostControllerSwitchBehavior=never

After that, restart your system.

After a reboot, I was able to map my Bluetooth adapter to parallels like I used to be able to. Hope that helps you all!

Thanks for the post.. It solved mine..

TaraM1 · Nov 3, 2019

JacobJ2 said:
I think I've found a workaround for this problem (and don't think it is Parallels that is at fault here). After doing some digging around in Apple's Bluetooth Explorer development tool, I discovered that macOS Catalina is actually attempting to use my external bluetooth adapter/dongle as the Bluetooth host controller for macOS. Because the bluetooth adapter is "in use" by macOS, it can't be mapped to the VM. This did NOT used to be the default behavior for macOS. A little searching around and I found you can instruct macOS to not use external adapters as host controllers by typing the following in terminal.

Code:

sudo nvram bluetoothHostControllerSwitchBehavior=never

After that, restart your system.

After a reboot, I was able to map my Bluetooth adapter to parallels like I used to be able to. Hope that helps you all!

Can you please walk me through this process step by step? I'm desperate here to get my dongle to work like it used to. I'm not sure where to enter the code.

TaraM1 · Nov 3, 2019

TaraM1 said:
Can you please walk me through this process step by step? I'm desperate here to get my dongle to work like it used to. I'm not sure where to enter the code.

Nvm. I was able to be walked through it by Parallels after telling them what I needed done per your above suggestion. Thank you so much!!!!!

Indivara · Nov 3, 2019

JacobJ2 said:
I think I've found a workaround for this problem (and don't think it is Parallels that is at fault here). After doing some digging around in Apple's Bluetooth Explorer development tool, I discovered that macOS Catalina is actually attempting to use my external bluetooth adapter/dongle as the Bluetooth host controller for macOS. Because the bluetooth adapter is "in use" by macOS, it can't be mapped to the VM. This did NOT used to be the default behavior for macOS. A little searching around and I found you can instruct macOS to not use external adapters as host controllers by typing the following in terminal.

Code:

sudo nvram bluetoothHostControllerSwitchBehavior=never

After that, restart your system.

After a reboot, I was able to map my Bluetooth adapter to parallels like I used to be able to. Hope that helps you all!

Thank you! This setting solved the issue.
For anyone visiting in future - here's the documentation for the setting - https://developer.apple.com/library/archive/technotes/tn2295/_index.html
Related question on Stack Exchange - https://apple.stackexchange.com/que...uetooth-dongle-instead-of-built-in-controller

I contacted Parallels support regarding this but they only want me to upgrade to Parallels 15. For the record, I had already confirmed the issue exists on both 14 and 15 (as stated in the original post), upgrading would be just a waste of money. (Parallels 14 already supports MacOS Catalina, though there is a caveat about compatibility issues. https://kb.parallels.com/114381)

DanielC31 · Nov 5, 2020

JacobJ2 said:
I think I've found a workaround for this problem (and don't think it is Parallels that is at fault here). After doing some digging around in Apple's Bluetooth Explorer development tool, I discovered that macOS Catalina is actually attempting to use my external bluetooth adapter/dongle as the Bluetooth host controller for macOS. Because the bluetooth adapter is "in use" by macOS, it can't be mapped to the VM. This did NOT used to be the default behavior for macOS. A little searching around and I found you can instruct macOS to not use external adapters as host controllers by typing the following in terminal.

Code:

sudo nvram bluetoothHostControllerSwitchBehavior=never

After that, restart your system.

After a reboot, I was able to map my Bluetooth adapter to parallels like I used to be able to. Hope that helps you all!

I was having the exact same problem and this solved it for me. Thank you very much!