@gouneken multiple inheritance of QObject isn't possible (Page_all class) your Page_all class inherits QWebEnginePage and also has a QWebEnginePage as a member variable?! dont name variables the same as their type names! the createWindow() method is intended to create a new physical window (a QWidget for example) and return the containing QWebEnginePage. You might need to create another QWebEngineView inside (or a use it directly as a window)

@Asif-QtAddict Oh! Well I have no idea why a 64-bit Chromium should behave any differently from a 32-bit one. If all it is is that it happens to be faster, presumably the problem will re-arise when the operation takes longer. Who knows!

https://stackoverflow.com/questions/58875159/how-to-ignore-ssl-certificate-errors-with-qwebengineview link helped me to resolve the issue. Now HTTPS page load after ignoring ssl warning is fine. Thanks for ideas :)

@comy said in Does QWebEnginePage::load() start a new event loop internally or it just calls processEvents() ?: @JonB Starting a new local event loop is done by executing QEventLoop::exec(). Oh I see, just QEventLoop::exec(). Yes, I had tried that. According to me it made no difference, and deleteLater()s of QWebEngine stuff still didn't free till execution got back to my top-level Qt event loop. Didn't understand why, your mileage may vary :)

Ok so I managed to import the html by modeling my code similar to the example with: QString code = QStringLiteral("qt.jQuery('#first_page').load('html/first_page.html');"); //you can even nest it with: QString code = QStringLiteral( "qt.jQuery('#first_page').load('html/first_page.html', ()=>{" "qt.jQuery('#border_content').load('html/border_content.html', ()=>{" //some other html "qt.jQuery('#last_page').load('html/last_page.html');" "});" "});" ); unfortunately I now cannot use the qwebchannel.js script anymore and my css gets screwed :( even loading it with: QFile script_file(":/qtwebchannel/qwebchannel.js"); if(!script_file.open(QIODevice::ReadOnly)) qDebug()<<"Couldn't load Qt's QWebChannel API!"; QString qt_script = QString::fromLatin1(script_file.readAll()); script_file.close(); view->page()->runJavaScript(qt_script); did not help. Since it is a small project and I am on a short deadline right now I will put everything in one html file and mark this question als solved.

@mpergand you are right, this line solved the problem. Thank you very much!