【Error:qt.bluetooth: Dummy backend running】with Running Bluetooth Examples

[Alex_wang]

Qt5 version :　5.8.0
System : Ubuntu 16.04
bluetooth version : 5.37

I am starting to do some work with QBluetooth, and find an example "Bluetooth Scanner Example", run it on ubuntu 16.04 .
Then the error is :
qt.bluetooth: Dummy backend running ; Qt Bluetooth module is non-functional

[jsulm]

@Alex_wang Try to start the app with QT_DEBUG_PLUGINS environment variable set:

QT_DEBUG_PLUGINS=1 && ./my_app

Then post the output. Most probably Bluez library is not installed on your machine.

[Alex_wang]

hi,
I try to run the app with

QT_DEBUG_PLUGINS=1 && ./my_app

print is :

Unable to query physical screen size, defaulting to 100 dpi.
To override, set QT_QPA_EGLFS_PHYSICAL_WIDTH and QT_QPA_EGLFS_PHYSICAL_HEIGHT (in millimeters).
qt.bluetooth: Dummy backend running. Qt Bluetooth module is non-functional.

And the bluez has been installed, I can use hciconfig hcitool to scan the devices.

[jsulm]

@Alex_wang You should have much more output when starting with QT_DEBUG_PLUGINS set.