https://bugs.kde.org/show_bug.cgi?id=509192
https://bugreports.qt.io/browse/QTBUG-140018
https://codereview.qt-project.org/c/qt/qtdeclarative/+/681080
--- a/src/quicktemplates/qquickstackelement.cpp
+++ b/src/quicktemplates/qquickstackelement.cpp
@@ -41,3 +41,5 @@
         auto privIncubator = QQmlIncubatorPrivate::get(this);
-        element->incubate(object, privIncubator->requiredProperties());
+        if (QQmlEnginePrivate *enginePriv = privIncubator->enginePriv) {
+            element->incubate(enginePriv->v4engine(), object, privIncubator->requiredProperties());
+        }
     }
@@ -92,3 +94,4 @@
 
-QQuickStackElement *QQuickStackElement::fromString(const QString &str, QQuickStackView *view, QString *error)
+QQuickStackElement *QQuickStackElement::fromString(
+        QQmlEngine *engine, const QString &str, QQuickStackView *view, QString *error)
 {
@@ -104,3 +107,3 @@
     QQuickStackElement *element = new QQuickStackElement;
-    element->component = new QQmlComponent(qmlEngine(view), url, view);
+    element->component = new QQmlComponent(engine, url, view);
     element->ownComponent = true;
@@ -129,3 +132,4 @@
 
-QQuickStackElement *QQuickStackElement::fromStackViewArg(QQuickStackView *view, QQuickStackViewArg arg)
+QQuickStackElement *QQuickStackElement::fromStackViewArg(
+        QQmlEngine *engine, QQuickStackView *view, QQuickStackViewArg arg)
 {
@@ -146,3 +150,3 @@
     } else if (arg.mUrl.isValid()) {
-        element->component = new QQmlComponent(qmlEngine(view), arg.mUrl, view);
+        element->component = new QQmlComponent(engine, arg.mUrl, view);
         element->ownComponent = true;
@@ -154,3 +158,3 @@
 
-bool QQuickStackElement::load(QQuickStackView *parent)
+bool QQuickStackElement::load(QV4::ExecutionEngine *v4, QQuickStackView *parent)
 {
@@ -163,3 +167,3 @@
                 if (status == QQmlComponent::Ready)
-                    load(view);
+                    load(component->engine()->handle(), view);
                 else if (status == QQmlComponent::Error)
@@ -179,3 +183,3 @@
     } else {
-        initialize(/*required properties=*/nullptr);
+        initialize(v4, /*required properties=*/nullptr);
     }
@@ -184,3 +188,4 @@
 
-void QQuickStackElement::incubate(QObject *object, RequiredProperties *requiredProperties)
+void QQuickStackElement::incubate(
+        QV4::ExecutionEngine *v4, QObject *object, RequiredProperties *requiredProperties)
 {
@@ -190,3 +195,3 @@
         item->setParent(view);
-        initialize(requiredProperties);
+        initialize(v4, requiredProperties);
     }
@@ -194,3 +199,4 @@
 
-void QQuickStackElement::initialize(RequiredProperties *requiredProperties)
+void QQuickStackElement::initialize(
+        QV4::ExecutionEngine *v4, RequiredProperties *requiredProperties)
 {
@@ -207,7 +213,4 @@
     if (!properties.isUndefined()) {
-        QQmlEngine *engine = qmlEngine(view);
-        Q_ASSERT(engine);
-        QV4::ExecutionEngine *v4 = QQmlEnginePrivate::getV4Engine(engine);
-        Q_ASSERT(v4);
         QV4::Scope scope(v4);
+        Q_ASSERT(scope.engine);
         QV4::ScopedValue ipv(scope, properties.value());
--- a/src/quicktemplates/qquickstackelement_p_p.h
+++ b/src/quicktemplates/qquickstackelement_p_p.h
@@ -45,9 +45,10 @@
 
-    static QQuickStackElement *fromString(const QString &str, QQuickStackView *view, QString *error);
+    static QQuickStackElement *fromString(QQmlEngine *engine, const QString &str, QQuickStackView *view, QString *error);
     static QQuickStackElement *fromObject(QObject *object, QQuickStackView *view, QString *error);
-    static QQuickStackElement *fromStackViewArg(QQuickStackView *view, QQuickStackViewArg arg);
+    static QQuickStackElement *fromStackViewArg(QQmlEngine *engine, QQuickStackView *view, QQuickStackViewArg arg);
 
-    bool load(QQuickStackView *parent);
-    void incubate(QObject *object, RequiredProperties *requiredProperties);
-    void initialize(RequiredProperties *requiredProperties);
+    bool load(QV4::ExecutionEngine *v4, QQuickStackView *parent);
+    void incubate(
+            QV4::ExecutionEngine *v4, QObject *object, RequiredProperties *requiredProperties);
+    void initialize(QV4::ExecutionEngine *v4, RequiredProperties *requiredProperties);
 
--- a/src/quicktemplates/qquickstackview.cpp
+++ b/src/quicktemplates/qquickstackview.cpp
@@ -459,4 +459,8 @@
     if (element) {
-        if (behavior == ForceLoad)
-            element->load(this);
+        if (behavior == ForceLoad) {
+            // It's possible for a slot to still be connected during destruction of the receiver's
+            // parent (QTBUG-140018), so only try to load new things if our engine is alive.
+            if (QQmlEngine *engine = qmlEngine(this))
+                element->load(engine->handle(), this);
+        }
         return element->item;
@@ -494,3 +498,3 @@
         if (behavior == ForceLoad)
-            element->load(this);
+            element->load(engine->handle(), this);
         if (element->item) {
@@ -626,3 +630,3 @@
     int oldDepth = d->elements.size();
-    if (d->pushElements(elements)) {
+    if (d->pushElements(v4, elements)) {
         d->depthChange(d->elements.size(), oldDepth);
@@ -739,3 +743,3 @@
 
-    if (d->popElements(enter)) {
+    if (d->popElements(v4, enter)) {
         if (exit) {
@@ -909,3 +913,3 @@
 
-    if (exit != target ? d->replaceElements(target, elements) : d->pushElements(elements)) {
+    if (exit != target ? d->replaceElements(v4, target, elements) : d->pushElements(v4, elements)) {
         d->depthChange(d->elements.size(), oldDepth);
@@ -993,2 +997,6 @@
 
+    QQmlEngine *engine = qmlEngine(this);
+    if (!engine)
+        return nullptr;
+
     QScopedValueRollback<bool> modifyingElements(d->modifyingElements, true);
@@ -996,3 +1004,3 @@
 
-    const QList<QQuickStackElement *> stackElements = d->parseElements(args);
+    const QList<QQuickStackElement *> stackElements = d->parseElements(engine, args);
 
@@ -1005,3 +1013,3 @@
     const int oldDepth = d->elements.size();
-    if (d->pushElements(stackElements)) {
+    if (d->pushElements(engine->handle(), stackElements)) {
         d->depthChange(d->elements.size(), oldDepth);
@@ -1111,3 +1119,7 @@
     Q_D(QQuickStackView);
-    return d->popToItem(item, operation, QQuickStackViewPrivate::CurrentItemPolicy::DoNotPop);
+    QQmlEngine *engine = qmlEngine(this);
+    if (!engine)
+        return nullptr;
+    return d->popToItem(
+            engine->handle(), item, operation, QQuickStackViewPrivate::CurrentItemPolicy::DoNotPop);
 }
@@ -1151,4 +1163,9 @@
     QQuickStackElement *element = d->elements.at(index);
-    element->load(this);
-    return d->popToItem(element->item, operation, QQuickStackViewPrivate::CurrentItemPolicy::Pop);
+    QQmlEngine *engine = qmlEngine(this);
+    if (!engine)
+        return nullptr;
+    QV4::ExecutionEngine *v4 = engine->handle();
+    element->load(v4, this);
+    return d->popToItem(
+            v4, element->item, operation, QQuickStackViewPrivate::CurrentItemPolicy::Pop);
 }
@@ -1180,3 +1197,9 @@
     }
-    return d->popToItem(d->currentItem, operation, QQuickStackViewPrivate::CurrentItemPolicy::Pop);
+
+    QQmlEngine *engine = qmlEngine(this);
+    if (!engine)
+        return nullptr;
+    return d->popToItem(
+            engine->handle(), d->currentItem, operation,
+            QQuickStackViewPrivate::CurrentItemPolicy::Pop);
 }
@@ -1234,2 +1257,6 @@
 
+    QQmlEngine *engine = qmlEngine(this);
+    if (!engine)
+        return nullptr;
+
     QScopedValueRollback<bool> modifyingElements(d->modifyingElements, true);
@@ -1239,3 +1266,3 @@
 
-    const QList<QQuickStackElement *> stackElements = d->parseElements(args);
+    const QList<QQuickStackElement *> stackElements = d->parseElements(engine, args);
 
@@ -1247,4 +1274,4 @@
     const bool successfullyReplaced = exit != currentElement
-        ? d->replaceElements(currentElement, stackElements)
-        : d->pushElements(stackElements);
+        ? d->replaceElements(engine->handle(), currentElement, stackElements)
+        : d->pushElements(engine->handle(), stackElements);
     if (successfullyReplaced) {
@@ -1609,2 +1636,7 @@
     int oldDepth = d->elements.size();
+
+    QQmlEngine *engine = qmlEngine(this);
+    if (!engine)
+        return;
+
     if (QObject *o = d->initialItem.toQObject())
@@ -1612,3 +1644,3 @@
     else if (d->initialItem.isString())
-        element = QQuickStackElement::fromString(d->initialItem.toString(), this, &error);
+        element = QQuickStackElement::fromString(engine, d->initialItem.toString(), this, &error);
     if (!error.isEmpty()) {
@@ -1616,3 +1648,3 @@
         delete element;
-    } else if (d->pushElement(element)) {
+    } else if (d->pushElement(engine->handle(), element)) {
         d->depthChange(d->elements.size(), oldDepth);
--- a/src/quicktemplates/qquickstackview_p.cpp
+++ b/src/quicktemplates/qquickstackview_p.cpp
@@ -111,3 +111,4 @@
 
-QList<QQuickStackElement *> QQuickStackViewPrivate::parseElements(const QList<QQuickStackViewArg> &args)
+QList<QQuickStackElement *> QQuickStackViewPrivate::parseElements(
+        QQmlEngine *engine, const QList<QQuickStackViewArg> &args)
 {
@@ -143,4 +144,4 @@
 
-        QQuickStackElement *element = QQuickStackElement::fromStackViewArg(q, arg);
-        QV4::ExecutionEngine *v4Engine = qmlEngine(q)->handle();
+        QQuickStackElement *element = QQuickStackElement::fromStackViewArg(engine, q, arg);
+        QV4::ExecutionEngine *v4Engine = engine->handle();
         element->properties.set(v4Engine, v4Engine->fromVariant(properties));
@@ -185,3 +186,4 @@
 
-QQuickStackElement *QQuickStackViewPrivate::createElement(const QV4::Value &value, const QQmlRefPointer<QQmlContextData> &context, QString *error)
+QQuickStackElement *QQuickStackViewPrivate::createElement(
+        const QV4::Value &value, const QQmlRefPointer<QQmlContextData> &context, QString *error)
 {
@@ -189,3 +191,4 @@
     if (const QV4::String *s = value.as<QV4::String>())
-        return QQuickStackElement::fromString(resolvedUrl(s->toQString(), context), q, error);
+        return QQuickStackElement::fromString(
+                s->engine()->qmlEngine(), resolvedUrl(s->toQString(), context), q, error);
     if (const QV4::QObjectWrapper *o = value.as<QV4::QObjectWrapper>())
@@ -193,9 +196,11 @@
     if (const QV4::UrlObject *u = value.as<QV4::UrlObject>())
-        return QQuickStackElement::fromString(resolvedUrl(u->href(), context), q, error);
+        return QQuickStackElement::fromString(
+                u->engine()->qmlEngine(), resolvedUrl(u->href(), context), q, error);
 
-    if (value.as<QV4::Object>()) {
+    if (const QV4::Object *o = value.as<QV4::Object>()) {
         const QVariant data = QV4::ExecutionEngine::toVariant(value, QMetaType::fromType<QUrl>());
         if (data.typeId() == QMetaType::QUrl) {
-            return QQuickStackElement::fromString(resolvedUrl(data.toUrl(), context).toString(), q,
-                                                  error);
+            return QQuickStackElement::fromString(
+                    o->engine()->qmlEngine(), resolvedUrl(data.toUrl(), context).toString(), q,
+                    error);
         }
@@ -206,3 +211,4 @@
 
-bool QQuickStackViewPrivate::pushElements(const QList<QQuickStackElement *> &elems)
+bool QQuickStackViewPrivate::pushElements(
+        QV4::ExecutionEngine *v4, const QList<QQuickStackElement *> &elems)
 {
@@ -214,3 +220,3 @@
         }
-        return elements.top()->load(q);
+        return elements.top()->load(v4, q);
     }
@@ -219,6 +225,6 @@
 
-bool QQuickStackViewPrivate::pushElement(QQuickStackElement *element)
+bool QQuickStackViewPrivate::pushElement(QV4::ExecutionEngine *v4, QQuickStackElement *element)
 {
     if (element)
-        return pushElements(QList<QQuickStackElement *>() << element);
+        return pushElements(v4, QList<QQuickStackElement *>() << element);
     return false;
@@ -226,3 +232,3 @@
 
-bool QQuickStackViewPrivate::popElements(QQuickStackElement *element)
+bool QQuickStackViewPrivate::popElements(QV4::ExecutionEngine *v4, QQuickStackElement *element)
 {
@@ -234,6 +240,8 @@
     }
-    return elements.top()->load(q);
+    return elements.top()->load(v4, q);
 }
 
-bool QQuickStackViewPrivate::replaceElements(QQuickStackElement *target, const QList<QQuickStackElement *> &elems)
+bool QQuickStackViewPrivate::replaceElements(
+        QV4::ExecutionEngine *v4, QQuickStackElement *target,
+        const QList<QQuickStackElement *> &elems)
 {
@@ -247,6 +255,8 @@
     }
-    return pushElements(elems);
+    return pushElements(v4, elems);
 }
 
-QQuickItem *QQuickStackViewPrivate::popToItem(QQuickItem *item, QQuickStackView::Operation operation, CurrentItemPolicy currentItemPolicy)
+QQuickItem *QQuickStackViewPrivate::popToItem(
+        QV4::ExecutionEngine *v4, QQuickItem *item, QQuickStackView::Operation operation,
+        CurrentItemPolicy currentItemPolicy)
 {
@@ -303,3 +313,3 @@
     QQuickItem *previousItem = nullptr;
-    if (popElements(enter)) {
+    if (popElements(v4, enter)) {
         if (exit) {
--- a/src/quicktemplates/qquickstackview_p_p.h
+++ b/src/quicktemplates/qquickstackview_p_p.h
@@ -52,3 +52,3 @@
     QList<QQuickStackElement *> parseElements(int from, QQmlV4FunctionPtr args, QStringList *errors);
-    QList<QQuickStackElement *> parseElements(const QList<QQuickStackViewArg> &args);
+    QList<QQuickStackElement *> parseElements(QQmlEngine *engine, const QList<QQuickStackViewArg> &args);
     QQuickStackElement *findElement(QQuickItem *item) const;
@@ -56,6 +56,6 @@
     QQuickStackElement *createElement(const QV4::Value &value, const QQmlRefPointer<QQmlContextData> &context, QString *error);
-    bool pushElements(const QList<QQuickStackElement *> &elements);
-    bool pushElement(QQuickStackElement *element);
-    bool popElements(QQuickStackElement *element);
-    bool replaceElements(QQuickStackElement *element, const QList<QQuickStackElement *> &elements);
+    bool pushElements(QV4::ExecutionEngine *v4, const QList<QQuickStackElement *> &elements);
+    bool pushElement(QV4::ExecutionEngine *v4, QQuickStackElement *element);
+    bool popElements(QV4::ExecutionEngine *v4, QQuickStackElement *element);
+    bool replaceElements(QV4::ExecutionEngine *v4, QQuickStackElement *element, const QList<QQuickStackElement *> &elements);
 
@@ -65,3 +65,3 @@
     };
-    QQuickItem *popToItem(QQuickItem *item, QQuickStackView::Operation operation, CurrentItemPolicy currentItemPolicy);
+    QQuickItem *popToItem(QV4::ExecutionEngine *v4, QQuickItem *item, QQuickStackView::Operation operation, CurrentItemPolicy currentItemPolicy);