QtBluetooth crashes at discoverDetails on Win11

[Hendrik B]

Hello Community!

I've written a Qt application in python on windows 11 using PyQt 6.5.1.

On windows 10 it worked fine to scan for devices, connect to one (that I also developped myself, so I have access to the clients GATT details), discover services and discover details of a specific service.

Now I upgraded to windows 11 due to customer requirements and the program freezes as soon as I call discoverDetails.

Snapshot of the code:

def serviceDiscovered(self, serviceUuid):
        print("service discovered... " + str(serviceUuid))
        if (serviceUuid == QBluetoothUuid("00000100-a2f9-45da-988f-c3517912fa9f")):
            print("service recognized")
            self.bleService = self.bleCentral.createServiceObject(serviceUuid)
            if self.bleService:
                self.bleService.stateChanged.connect(self.serviceStateChanged, type=Qt.ConnectionType.QueuedConnection)
                self.bleService.characteristicChanged.connect(self.updateValues, type=Qt.ConnectionType.QueuedConnection)
                self.bleService.characteristicRead.connect(self.dataRead, type=Qt.ConnectionType.QueuedConnection)
                self.bleService.descriptorWritten.connect(self.confirmedDescriptorWrite, type=Qt.ConnectionType.QueuedConnection)
                self.bleService.errorOccurred.connect(self.bleServiceError, type=Qt.ConnectionType.QueuedConnection)
                ## Here an error occurs in WIN 11... program (Qt GUI) freezes
                self.bleService.discoverDetails(QLowEnergyService.DiscoveryMode.SkipValueDiscovery)

Any help or hints appreciated, also telling me if it perfectly works for you would help, then maybe the error is to be searched on the clients side... however, it did work well on windows 10.

Best regards, Hendrik

[neilw404]

I appear to have the same problem. discoverDetails gets stuck in some kind of infinite loop on Win11.

Has anyone else seen this? Or found a way round it?

I am running on PySide6 v.6.6.

I have checked the threads:

41744, 12.38, 2,876,720,284, python.exe+0x12a0, Normal
45740, 0.02, 5,287,066, winmm.dll!PlaySoundW+0xe30, Time critical
18724, 0.01, 3,369,858, ucrtbase.dll!recalloc+0x10, Normal
51356, , 1,301,246, ucrtbase.dll!recalloc+0x10, Normal
18760, , 874,602, ucrtbase.dll!recalloc+0x10, Normal
52100, , , ntdll.dll!RtlClearThreadWorkOnBehalfTicket+0x70, Normal
46912, , , ntdll.dll!RtlClearThreadWorkOnBehalfTicket+0x70, Normal
45108, , , Qt6Core.dll!QThread::start+0x2d0, Normal
41732, , , ntdll.dll!RtlClearThreadWorkOnBehalfTicket+0x70, Normal
41424, , , combase.dll!CoIncrementMTAUsage+0x3590, Normal
41208, , , ucrtbase.dll!recalloc+0x10, Normal
32288, , , ntdll.dll!RtlClearThreadWorkOnBehalfTicket+0x70, Normal
11612, , , igd10um64xe.dll!OpenAdapter10_2+0x3e730, Normal
7644, , , Qt6Core.dll!QThread::start+0x2d0, Normal
3404, , , igd10um64xe.dll!OpenAdapter10_2+0x3e730, Normal

The busiest thread (41744) looks reasonable enough:

0, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x103c8
1, Qt6Bluetooth.dll!QBluetoothLocalDevice::setHostMode+0x104d
2, Qt6Bluetooth.dll!QBluetoothServer::setMaxPendingConnections+0x16770
3, Qt6Bluetooth.dll!QBluetoothServer::setMaxPendingConnections+0x12c7b
4, Qt6Bluetooth.dll!QBluetoothServer::setMaxPendingConnections+0xfb9d
5, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x22a5e
6, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x311c2
7, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x21661
8, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x2159c
9, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x129ee
10, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x1d1d1
11, Windows.Devices.Bluetooth.dll!DllGetClassObject+0x29eff
12, combase.dll!Ordinal111+0x7bd6
13, combase.dll!Ordinal111+0x79d4
14, combase.dll!Ordinal139+0x14214
15, combase.dll!CoIsHandlerConnected+0x2022
16, combase.dll!CStdStubBuffer_DebugServerRelease+0x177e4
17, user32.dll!DispatchMessageW+0x741
18, user32.dll!DispatchMessageW+0x201
19, Qt6Core.dll!QEventDispatcherWin32::processEvents+0x53a
20, Qt6Gui.dll!QWindowsGuiEventDispatcher::processEvents+0x19
21, Qt6Core.dll!QEventLoop::exec+0x19f
22, Qt6Core.dll!QCoreApplication::exec+0x15d
23, QtCore.pyd!PyInit_QtCore+0x17caf0
24, python310.dll!PyObject_GC_Malloc+0x2e0
25, python310.dll!PyErr_NormalizeException+0x555
26, python310.dll!PyErr_NormalizeException+0x2cf
27, python310.dll!PyErr_NormalizeException+0x28c
28, python310.dll!PyEval_EvalFrameDefault+0xa5c4
29, python310.dll!PyMapping_Check+0x311
30, python310.dll!PyEval_EvalCode+0x82
31, python310.dll!PyEval_GetBuiltins+0x70b
32, python310.dll!PyEval_GetBuiltins+0x60b
33, python310.dll!PyObject_GetBuffer+0xd59
34, python310.dll!PyErr_NormalizeException+0x555
35, python310.dll!PyErr_NormalizeException+0x2cf
36, python310.dll!PyErr_NormalizeException+0x28c
37, python310.dll!Py_gitversion+0x20628
38, python310.dll!PyFunction_Vectorcall+0x87
39, python310.dll!PyErr_NormalizeException+0x555
40, python310.dll!PyErr_NormalizeException+0x2cf
41, python310.dll!Py_gitversion+0x2c350
42, python310.dll!Py_gitversion+0x20628
43, python310.dll!PyFunction_Vectorcall+0x87
44, python310.dll!PyErr_NormalizeException+0x555
45, python310.dll!PyErr_NormalizeException+0x2cf
46, python310.dll!Py_gitversion+0x2c350
47, python310.dll!Py_gitversion+0x20ced
48, python310.dll!PyFunction_Vectorcall+0x87
49, python310.dll!PyErr_NormalizeException+0x555
50, python310.dll!PyErr_NormalizeException+0x2cf
51, python310.dll!Py_gitversion+0x2c350
52, python310.dll!Py_gitversion+0x20ced
53, python310.dll!PyFunction_Vectorcall+0x87
54, python310.dll!PyEval_EvalFrameDefault+0x5f4
55, python310.dll!PyFunction_Vectorcall+0x87
56, python310.dll!PyEval_EvalFrameDefault+0x1a3b
57, python310.dll!PyMapping_Check+0x311
58, python310.dll!PyEval_EvalCode+0x82
59, python310.dll!PyEval_GetBuiltins+0x70b
60, python310.dll!PyEval_GetBuiltins+0x60b
61, python310.dll!PyEval_EvalFrameDefault+0x1957
62, python310.dll!PyFunction_Vectorcall+0x87
63, python310.dll!PyEval_EvalFrameDefault+0x5f4
64, python310.dll!PyFunction_Vectorcall+0x87
65, python310.dll!PyVectorcall_Call+0x5c
66, python310.dll!PyObject_Call+0x4f
67, python310.dll!PyArg_Parse+0x1ba
68, python310.dll!Py_RunMain+0x13d
69, python310.dll!Py_RunMain+0x15
70, python310.dll!Py_Main+0x25
71, python.exe+0x1230
72, kernel32.dll!BaseThreadInitThunk+0x1d
73, ntdll.dll!RtlUserThreadStart+0x28

But the second busiest thread (45740)... I' don't know what it's up to:

0, ntdll.dll!ZwWaitForMultipleObjects+0x14
1, winmm.dll!PlaySoundW+0xec1
2, kernel32.dll!BaseThreadInitThunk+0x1d
3, ntdll.dll!RtlUserThreadStart+0x28

Here is the complete thread list:

[wenyin]

@Hendrik-B Did you find a solution to the problem?

[Rida Shamasneh]

I wonder how much time would it require to fix this issue!
I reported this issue 1.5 years ago and no real help. This is frustrating!

[wenyin]

This post is deleted!

[Rida Shamasneh]

I have shared a solution to this issue on the following bug report:
https://bugreports.qt.io/browse/QTBUG-109510

[JonB]

@Rida-Shamasneh
Although this is not my area I read through the bug report and thank you for contributing your workaround for the community.

I am just intrigued about one thing: why is this a Python/PyQt/PySide issue, yet (apparently) not from C++?

[Cagnulein]

This post is deleted!