qt.network.ssl: No functional TLS backend was found ?

BVladimir

Hello !

I am trying to "call" my с++ dll with qt 6.2.1 from python 3.9. A lot of errors:

"qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No TLS backend is available"
console with QT_DEBUG_PLUGINS:

QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2d.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2d.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"direct2d"
]
},
"archreq": 0,
"className": "QWindowsDirect2DIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2d.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2dd.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2dd.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"direct2d"
]
},
"archreq": 1,
"className": "QWindowsDirect2DIntegrationPlugin",
"debug": true,
"version": 393728
}

Got keys from plugin meta data QList("direct2d")
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimal.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimal.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archreq": 0,
"className": "QMinimalIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimal.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimald.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimald.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archreq": 1,
"className": "QMinimalIntegrationPlugin",
"debug": true,
"version": 393728
}

Got keys from plugin meta data QList("minimal")
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreen.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreen.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archreq": 0,
"className": "QOffscreenIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreen.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreend.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreend.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archreq": 1,
"className": "QOffscreenIntegrationPlugin",
"debug": true,
"version": 393728
}

Got keys from plugin meta data QList("offscreen")
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindows.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindows.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"windows"
]
},
"archreq": 0,
"className": "QWindowsIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindows.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindowsd.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindowsd.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"windows"
]
},
"archreq": 1,
"className": "QWindowsIntegrationPlugin",
"debug": true,
"version": 393728
}

Got keys from plugin meta data QList("windows")
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39" ...
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/python3.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/python3.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/python39.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/python39.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/vcruntime140.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/vcruntime140.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/vcruntime140_1.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/vcruntime140_1.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/platforms" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39/platforms" ...
loaded library "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindowsd.dll"
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2d.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2d.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"direct2d"
]
},
"archreq": 0,
"className": "QWindowsDirect2DIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2d.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qdirect2dd.dll"
Got keys from plugin meta data QList()
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimal.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimal.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archreq": 0,
"className": "QMinimalIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimal.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qminimald.dll"
Got keys from plugin meta data QList()
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreen.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreen.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archreq": 0,
"className": "QOffscreenIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreen.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qoffscreend.dll"
Got keys from plugin meta data QList()
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindows.dll"
Found metadata in lib C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindows.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"windows"
]
},
"archreq": 0,
"className": "QWindowsIntegrationPlugin",
"debug": false,
"version": 393728
}

"The plugin 'C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindows.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/qwindowsd.dll"
Got keys from plugin meta data QList()
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39" ...
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/python3.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/python3.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/python39.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/python39.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/vcruntime140.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/vcruntime140.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() looking at "C:/Program Files/Python39/vcruntime140_1.dll"
"Failed to extract plugin meta data from 'C:/Program Files/Python39/vcruntime140_1.dll'"
not a plugin
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/platformthemes" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39/platformthemes" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/networkaccess" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39/networkaccess" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/tls" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39/tls" ...
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No TLS backend is available
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No TLS backend is available
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/accessiblebridge" ...
QFactoryLoader::QFactoryLoader() checking directory path "C:/Program Files/Python39/accessiblebridge" ...
QQmlApplicationEngine failed to load component
c:%5CC++%5Cfor_quik_lua535%5Cx64%5CDebug%5Cmain_window.qml: Network error

raven-worx

@BVladimir
make sure OpenSSL 1.1.x libs are in the PATH or next to your executable

BVladimir

Thanks.
But is openssl really necessary for the simplest qml window?

BVladimir

Does not work - version 1.1.1L- copied the content...\OpenSSL-Win64\lib to ...\x64\Debug where is my dll - nothing...

raven-worx

@BVladimir said in qt.network.ssl: No functional TLS backend was found ?:

But is openssl really necessary for the simplest qml window?

no, but it seems you are loading resources from secured network address (main_window.qml: Network error)

@BVladimir said in qt.network.ssl: No functional TLS backend was found ?:

Does not work - version 1.1.1L- copied the content...\OpenSSL-Win64\lib to ...\x64\Debug where is my dll - nothing...

as i said make sure they are in the PATH env variable or next to your executable.

BVladimir

I don't have an exe file, just a python script calling a function from a dll. The entire openssl lib is in the directory with the dll. In the dll itself, the only code from qt:

int argc = 1;
const char* p1{ "C" };
const char** argv = &p1;
QGuiApplication app(argc, (char**) argv);

QCoreApplication::addLibraryPath("C:\Program Files\OpenSSL-Win64\lib");
QQmlApplicationEngine engine;
const QUrl url(QStringLiteral("C:\C++\for_quik_lua535\x64\Debug\main_window.qml"));
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated, &app,
[url](QObject* obj, const QUrl& objUrl) { if (!obj && url == objUrl) QCoreApplication::exit(-1);},
Qt::QueuedConnection);
engine.load(url);
return PyLong_FromLong(app.exec());

SGaist

Hi,

That's not the purpose of addLibraryPath. As @raven-worx already suggested the .dlls should be findable in the PATH environment variable.

How are you starting your script ?

How did you install Python ?

Can you explain what your script does ?

BVladimir

addLibraryPath - just in case. env. path is set.
py script, starting from VS 2019, python 3.9 by standard installer:

from importlib.machinery import ExtensionFileLoader
dll = ExtensionFileLoader('py2quik_module', r'C:\C++\for_quik_lua535\x64\Debug\for_quik_lua535.dll').load_module()

if name == 'main':
py_obj = dll.py2dll_obj(None)

SGaist

@BVladimir said in qt.network.ssl: No functional TLS backend was found ?:

py2quik

Would you mind explaining what exactly you are trying to load ?

BVladimir

My dll "for_quik_lua535.dll" is a Python/C extension named "py2quik_module" in python

SGaist

Out of curiosity, why not use PySide or PyQt since you are already working with Python ?

BVladimir

I think it will work faster in c++ - a lot of online data is planned. Python for the general scenario.

SGaist

What kind of data do you intend to process ?

BVladimir

Data from stock exchange terminal

BVladimir

I tried to build an exe file:

#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char* argv[]) {
int argc2 = 1;
const char* p1{ "C" };
const char** argv2 = &p1;

QGuiApplication app(argc2, (char**)argv2);

QQmlApplicationEngine engine;
const QUrl url(QStringLiteral("qrc:tmpQML/tmpQML.qml"));
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
    &app, [url](QObject* obj, const QUrl& objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
engine.load(url);

return app.exec();

}

Same QML:

import QtQuick 2.12
import QtQuick.Controls 2.12

ApplicationWindow {

title: "Qt Quick Controls Gallery"
visible: true
width: 640
height: 480

}

When running from VS 2019, it works fine. And does not try to search any of:

QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/networkaccess" ...

or

QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/tls" ...

It's only with dll problem...

SGaist

What are going to use to process your data ?

BVladimir

The main idea is Python calls dll's that receive data and display using qt, General work with data where speed is not needed in Python

SGaist

Well, I must say I fail to understand your architecture here.

What is so speed critical in your app that you need to have your UI in C++ while doing some processing in Python while the rest is done in C++ again.

BVladimir

Data from stock exchange terminal - through с++ & qt, analysis in Python.

SGaist

Why not load the data directly in Python using something like numpy ?