plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered QML debugging is enabled...

alex_malyu

Installed Qt 5.15.2 with MinGW (32 and 64)

It works until I start importing QtQuick.Layouts and QtQuick.Controls
Debugging in QtCreator fails with:

import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Layouts 2.15
import QtQuick.Controls 2.15

In the meantime import is visible in QtCreator, if I remove import appropriate components are marked as not found.
Error looks like:

QQmlApplicationEngine failed to load component
qrc:/main.qml:3:1: plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered
QML debugging is enabled. Only use this in a safe environment.

I've seen the closed bug on similar issue.
I updated the qt today.
Nothing changed.

Anybody knows workaround?

alex_malyu

It seems bug was either re-introduced or never was fixed:

https://bugreports.qt.io/browse/QTBUG-81961?jql=text ~ "Cannot protect module QtQuick.Controls 2"

That's fixed by https://codereview.qt-project.org/c/qt/qtquickcontrols2/+/289223 but is prevented from getting in due to QTBUG-81772, which has a blacklist patch but another part of the test apparently crashes once the tests are blacklisted... ugh.
I think we can close this in any case.

I think closing critical bugs without having them pushed to repo is a bad choice.

In any case I need workaround, It is impossible to develop anything.
How does it work with other systems?

I used Qt 5.9.5 on Ubuntu, but need newer version now. Anybody can share which one works on Windows with MinGW?

SGaist

Hi,

The bug mentions Qt 6 and from the comments it has been fixed there.

If you have the same issue, you should comment on the bug report.

RokeJulianLockhart

If you have the same issue, you should comment on the bug report.

@SGaist, That issue appears to have been closed for a reason I don't understand. However, I've the same problem:

#!/usr/bin/env -S qml
import QtQuick 6.9
import QtQuick.Controls 6.9
import QtQuick.Layouts 6.9
ApplicationWindow {
	visible: true
	title: qsTr("Application Menu")
	RowLayout {
		anchors.centerIn: parent
		spacing: 10
		Label {
			text: "Hello from QML!"
		}
		Button {
			text: "Click Me"
			onClicked: console.log("Button clicked")
		}
	}
}

When I invoke this with qml $HOME/main.qml, I see "Cannot protect module QtQuick.Controls 6 as it was never registered":

QQmlApplicationEngine failed to load component
file:///home/RokeJulianLockhart/Documents/main.qml:3:1: plugin cannot be loaded for module "QtQuick.Controls": Cannot protect module QtQuick.Controls 6 as it was never registered
qml: Did not load any objects, exiting.

If I modify it to be more minimal:

#!/usr/bin/env -S qml
import QtQuick 6.9
ApplicationWindow {
	visible: true
	title: qsTr("Application Menu")
}

...I see:

main.qml:2:1: module "QtQuick" is not installed

This shouldn't be possible, because kinfo returns "Qt Version: 6.9.1":

Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.1
Kernel Version: 6.15.9-201.fc42.x86_64 (64-bit)
Graphics Platform: Wayland

Additionally, if I invoke at least the former version via Python, it works:

#!/usr/bin/env -S python3
import sys
from PySide6.QtCore import QUrl
from PySide6.QtGui import QGuiApplication
from PySide6.QtQml import QQmlApplicationEngine
if __name__ == "__main__":
	application_type_inherited_object = QGuiApplication(sys.argv)
	engine_inherited_object = QQmlApplicationEngine()
	qt_meta_object_language_file_uniform_resource_identifier = QUrl.fromLocalFile("main.qml")
	engine_inherited_object.load(qt_meta_object_language_file_uniform_resource_identifier)
	if not engine_inherited_object.rootObjects():
		sys.exit(-1)
	sys.exit(application_type_inherited_object.exec())

The reason I want to do this is because I can't diagnose faults in the QML otherwise; I use VS Code.

jsulm

@RokeJulianLockhart said in plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered QML debugging is enabled...:

This shouldn't be possible, because kinfo returns "Qt Version: 6.9.1":

Which does not mean that QtQuick is installed. Make sure it is installed.

RokeJulianLockhart

@jsulm, does what I demonstrated thereafter not confirm that it must be installed? Regardless, the lack of answer to stackoverflow.com/q/59612208 means I've no idea how to ascertain what version is installed (although it should be, and appears to be, 1:1 with the Qt version).

Note that I solely need to add the version when I invoke it with qml. However, even with that version specified, it works in VSC.

JKSH

@alex_malyu said in plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered QML debugging is enabled...:

I think closing critical bugs without having them pushed to repo is a bad choice.

As discussed at https://bugreports.qt.io/browse/QTBUG-81961, the bug report is invalid.

The problem is that you specified the wrong version for the import.

@RokeJulianLockhart said in plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered QML debugging is enabled...:

I see "Cannot protect module QtQuick.Controls 6 as it was never registered"

Try removing all the version numbers from your import statements. Version numbers are not required (or recommended) in Qt 6.

This shouldn't be possible, because kinfo returns "Qt Version: 6.9.1":

What does qml --version show? How about which qml?

RokeJulianLockhart

What does qml --version show? How about which qml?

@JKSH, sensible. Surprisingly, it appears to be from Qt 5:

RokeJulianLockhart@Beedell:~$ qml --version
Qml Runtime 5.15.17
RokeJulianLockhart@Beedell:~$ dnf5 provides $(command -v qml)
Updating and loading repositories:
Repositories loaded.
qt5-qtdeclarative-devel-5.15.17-1.fc42.x86_64 : Development files for qt5-qtdeclarative
Repo         : @System
Matched From : 
Filename     : /usr/bin/qml

qt5-qtdeclarative-devel-5.15.17-1.fc42.i686 : Development files for qt5-qtdeclarative
Repo         : updates
Matched From : 
Filename     : /usr/bin/qml

qt5-qtdeclarative-devel-5.15.17-1.fc42.x86_64 : Development files for qt5-qtdeclarative
Repo         : updates
Matched From : 
Filename     : /usr/bin/qml

qt5-qtdeclarative-devel-5.15.16-2.fc42.i686 : Development files for qt5-qtdeclarative
Repo         : fedora
Matched From : 
Filename     : /usr/bin/qml

qt5-qtdeclarative-devel-5.15.16-2.fc42.x86_64 : Development files for qt5-qtdeclarative
Repo         : fedora
Matched From : 
Filename     : /usr/bin/qml

RokeJulianLockhart@Beedell:~$ dnf5 info $(rpm -qa qt5-qtdeclarative-devel)
Updating and loading repositories:
Repositories loaded.
Installed packages
Name            : qt5-qtdeclarative-devel
Epoch           : 0
Version         : 5.15.17
Release         : 1.fc42
Architecture    : x86_64
Installed size  : 8.8 MiB
Source          : qt5-qtdeclarative-5.15.17-1.fc42.src.rpm
From repository : updates
Summary         : Development files for qt5-qtdeclarative
URL             : http://www.qt.io
License         : LGPL-3.0-only OR GPL-3.0-only WITH Qt-GPL-exception-1.0
Description     : Development files for qt5-qtdeclarative.
Vendor          : Fedora Project

Could a Qt 5 library have somehow acquired precedence in $Env:PATH? That might explain all my QML woes.

Try removing all the version numbers from your import statements. Version numbers are not required (or recommended) in Qt 6.

Glad to hear. Unfortunately, it doesn't improve anything. With:

#!/usr/bin/env -S qml
import QtQuick // 6.9
import QtQuick.Controls // 6.9
import QtQuick.Layouts // 6.9
ApplicationWindow {
	visible: true
	title: qsTr("Application Menu")
	RowLayout {
		anchors.centerIn: parent
		spacing: 10
		Label {
			text: "Hello from QML!"
		}
		Button {
			text: "Click Me"
			onClicked: console.log("Button clicked")
		}
	}
}

...I see:

main.qml: Library import requires a version

Thanks for the assistance, and apologies for the wait.

JKSH

@RokeJulianLockhart said in plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered QML debugging is enabled...:

Could a Qt 5 library have somehow acquired precedence in $Env:PATH? That might explain all my QML woes.

That's not it. That qml binary provided by your distro's official repository is based on Qt 5, so it cannot load Qt 6 code.

The solution is to avoid /usr/bin/qml which is based on Qt 5. You must either replace that with a Qt 6 version (if your distro supplies it), or use a custom-installed version instead (the Qt Online Installer will let you do ~/Qt/6.9.1/gcc_64/qml main.qml)

RokeJulianLockhart

@JKSH, turns out that I've been through this before, per post/820589. My sincere apologies. How I wish documentation online would cease to cite qml.

qml-qt6 ./main.qml works perfectly:

JKSH

@RokeJulianLockhart said in plugin cannot be loaded for module "QtQuick.Layouts": Cannot protect module QtQuick.Layouts 2 as it was never registered QML debugging is enabled...:

qml-qt6 ./main.qml works perfectly

Great! Thanks for sharing.

Just remember that you are bound to your distro's version of Qt 6, so the qml-qt6 tool won't be able to process QML code that uses functionality from newer versions.

The tool is also intended as a way to quickly preview *.qml files. It won't be able to handle custom types/classes defined from C++ or Python for example (unless you put your class in a C++ plugin that's formally installed)