pywebview works with python3.6.8 & python3.9.16 on redhat7 (RHEL7.9). But it doesn't work with python3.9.16 on redhat9 (RHEL9.2)

[justincui]

I tried three environments: python 3.6.8 on RHEL7, python3.9.16 on RHEL7, python 3.9.16 on RHEL9. I use the following command to install packages:

python3 -m pip install PyQt5==5.13.2
python3 -m pip install PyQtWebEngine==5.13.2
python3 -m pip install pywebview[qt]==4.1

The following are my code:

def prepare_window(window):
    window.events.shown += on_main_window_shown

#####################
api = Api()
window = webview.create_window('MyTool',
                               url=start_page,
                               js_api=api,
                               confirm_close=True,
                               text_select=True,
                               min_size=(640, 530))
api.set_windows(window)
webview.start(prepare_window, window,
              gui='qt',
              http_server=True,
              debug=True)

With python 3.6.8 on RHEL7 & python3.9.16 on RHEL7, both work perfectly.
With python 3.9.16 on RHEL9, it just pop up the main windows and display nothing. And the front-end debugger (the chrome js debugger window) doesn't show.
I've tried the latest PyQt5/PyQtWebEngine/pywebview[qt] and still doesn't work in the exact same way:

# installed with the single command "pip install pywebview[qt]"
proxy-tools       0.1.0
PyQt5             5.15.10
PyQt5-Qt5         5.15.2
PyQt5-sip         12.13.0
PyQtWebEngine     5.15.6
PyQtWebEngine-Qt5 5.15.2
pywebview         4.4.1
QtPy              2.4.1

The following simple pyqt5 webengine code has the same issue before and can be fixed by adding ['', '--no-sandbox'] to QApplication([]). so I tried to add ['', '--no-sandbox'] for QApplication([]) in the .venv/lib/python3.9/site-packages/webview/platforms/qt.py but it doesn't work.

import sys
import os
from PyQt5.QtWidgets import QWidget, QApplication, QVBoxLayout
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWebEngineWidgets import QWebEngineView
from qtpy import QtCore
local_dir = os.path.dirname(__file__)

class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):

        vbox = QVBoxLayout(self)

        self.webEngineView = QWebEngineView()
        self.loadPage()

        vbox.addWidget(self.webEngineView)

        self.setLayout(vbox)

        self.setGeometry(300, 300, 350, 250)
        self.setWindowTitle('QWebEngineView')
        self.show()

    def loadPage(self):
        #option1 (work):
        self.webEngineView.setUrl(QtCore.QUrl('http://127.0.0.1:31200/mytool.html'))
        
        #option2 (also work):
        # with open(f'{local_dir}/test.html', 'r') as f:

        #     html = f.read()
        #     self.webEngineView.setHtml(html)

def main():

    app = QApplication(sys.argv + ['', '--no-sandbox'])
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

[r0x0r]

There is an existing no sandbox logic enabled for some platforms found in

pywebview/webview/platforms/qt.py

Line 49 in 2d1833d

if is_webengine and QtCore.QSysInfo.productType() in ['arch', 'manjaro', 'nixos']:

Could you test if enabling it on RHEL9 solves the problem?

[justincui]

It really works!!!! I add 'rhel' and the problem is solved!
if is_webengine and QtCore.QSysInfo.productType() in ['arch', 'manjaro', 'nixos', 'rhel']:
Thanks a lot!