diff --git a/src/libs/utils/fancymainwindow.cpp b/src/libs/utils/fancymainwindow.cpp
index a06c060dd16..482c8ab5da1 100644
--- a/src/libs/utils/fancymainwindow.cpp
+++ b/src/libs/utils/fancymainwindow.cpp
@@ -590,11 +590,13 @@ Store FancyMainWindow::saveSettings() const
     return settings;
 }
 
-void FancyMainWindow::restoreSettings(const Store &settings)
+bool FancyMainWindow::restoreSettings(const Store &settings)
 {
+    bool success = true;
     QByteArray ba = settings.value(StateKey, QByteArray()).toByteArray();
     if (!ba.isEmpty()) {
-        if (!restoreFancyState(ba, settingsVersion))
+        success = restoreFancyState(ba, settingsVersion);
+        if (!success)
             qWarning() << "Restoring the state of dock widgets failed.";
     }
     d->m_showCentralWidget.setChecked(settings.value(ShowCentralWidgetKey, true).toBool());
@@ -603,6 +605,8 @@ void FancyMainWindow::restoreSettings(const Store &settings)
                             settings.value(keyFromString(widget->objectName()), false));
     }
     d->restoreHiddenDockAreasFromHash(settings.value(HiddenDockAreasKey).toHash());
+    emit dockWidgetsChanged();
+    return success;
 }
 
 bool FancyMainWindow::restoreFancyState(const QByteArray &state, int version)
diff --git a/src/libs/utils/fancymainwindow.h b/src/libs/utils/fancymainwindow.h
index 8967affb749..1c9fc6a38de 100644
--- a/src/libs/utils/fancymainwindow.h
+++ b/src/libs/utils/fancymainwindow.h
@@ -33,7 +33,7 @@ public:
     void saveSettings(QtcSettings *settings) const;
     void restoreSettings(const QtcSettings *settings);
     Store saveSettings() const;
-    void restoreSettings(const Store &settings);
+    bool restoreSettings(const Store &settings);
     bool restoreFancyState(const QByteArray &state, int version = 0);
 
     // Additional context menu actions
diff --git a/src/plugins/debugger/debuggermainwindow.cpp b/src/plugins/debugger/debuggermainwindow.cpp
index e87ef9e1741..16f0f8dface 100644
--- a/src/plugins/debugger/debuggermainwindow.cpp
+++ b/src/plugins/debugger/debuggermainwindow.cpp
@@ -437,8 +437,14 @@ void DebuggerMainWindow::restorePersistentSettings()
     d->m_lastTypePerspectiveStates.clear();
     QSet<QString> keys = Utils::toSet(states2.keys());
     for (const QString &type : keys) {
-        PerspectiveState state = states2.value(type).value<PerspectiveState>();
-        QTC_ASSERT(!state.mainWindowState.isEmpty(), continue);
+        PerspectiveState state;
+        if (states2.value(type).canConvert<QVariantMap>()) {
+            state = PerspectiveState::fromSettings(storeFromMap(states2.value(type).toMap()));
+        } else {
+            // legacy for up to QtC 12
+            state = states2.value(type).value<PerspectiveState>();
+        }
+        QTC_ASSERT(state.hasWindowState(), continue);
         d->m_lastTypePerspectiveStates.insert(type, state);
     }
 
@@ -469,7 +475,7 @@ void DebuggerMainWindow::savePersistentSettings() const
         qCDebug(perspectivesLog) << "PERSPECTIVE TYPE " << type
                                  << " HAS STATE: " << !state.mainWindowState.isEmpty();
         QTC_ASSERT(!state.mainWindowState.isEmpty(), continue);
-        states.insert(type, QVariant::fromValue(state));
+        states.insert(type, mapFromStore(state.toSettings()));
     }
 
     QtcSettings *settings = ICore::settings();
@@ -965,10 +971,10 @@ void PerspectivePrivate::restoreLayout()
 {
     qCDebug(perspectivesLog) << "RESTORE LAYOUT FOR " << m_id << settingsId();
     PerspectiveState state = theMainWindow->d->m_lastPerspectiveStates.value(m_id);
-    if (state.mainWindowState.isEmpty()) {
+    if (!state.hasWindowState()) {
         qCDebug(perspectivesLog) << "PERSPECTIVE STATE NOT AVAILABLE BY FULL ID.";
         state = theMainWindow->d->m_lastTypePerspectiveStates.value(settingsId());
-        if (state.mainWindowState.isEmpty()) {
+        if (state.hasWindowState()) {
             qCDebug(perspectivesLog) << "PERSPECTIVE STATE NOT AVAILABLE BY PERSPECTIVE TYPE";
         } else {
             qCDebug(perspectivesLog) << "PERSPECTIVE STATE AVAILABLE BY PERSPECTIVE TYPE.";
@@ -994,10 +1000,10 @@ void PerspectivePrivate::restoreLayout()
         }
     }
 
-    if (state.mainWindowState.isEmpty()) {
+    if (!state.hasWindowState()) {
         qCDebug(perspectivesLog) << "PERSPECTIVE " << m_id << "RESTORE NOT POSSIBLE, NO STORED STATE";
     } else {
-        bool result = theMainWindow->restoreFancyState(state.mainWindowState);
+        const bool result = state.restoreWindowState(theMainWindow);
         qCDebug(perspectivesLog) << "PERSPECTIVE " << m_id << "RESTORED, SUCCESS: " << result;
     }
 
@@ -1019,7 +1025,7 @@ void PerspectivePrivate::saveLayout()
 {
     qCDebug(perspectivesLog) << "PERSPECTIVE" << m_id << "SAVE LAYOUT TO " << settingsId();
     PerspectiveState state;
-    state.mainWindowState = theMainWindow->saveState();
+    state.mainWindowState = theMainWindow->saveSettings();
     for (DockOperation &op : m_dockOperations) {
         if (op.operationType != Perspective::Raise) {
             QTC_ASSERT(op.dock, continue);
@@ -1070,4 +1076,36 @@ const char *PerspectiveState::savesHeaderKey()
     return "SavesHeader";
 }
 
+bool PerspectiveState::hasWindowState() const
+{
+    return !mainWindowState.isEmpty() || !mainWindowStateLegacy.isEmpty();
+}
+
+bool PerspectiveState::restoreWindowState(FancyMainWindow * mainWindow)
+{
+    if (!mainWindowState.isEmpty())
+        return mainWindow->restoreSettings(mainWindowState);
+    if (!mainWindowStateLegacy.isEmpty())
+        return mainWindow->restoreFancyState(mainWindowStateLegacy);
+    return false;
+}
+
+const char kMainWindowStateKey[] = "MainWindow";
+const char kHeaderViewStatesKey[] = "HeaderViewStates";
+
+Store PerspectiveState::toSettings() const
+{
+    Store result;
+    result.insert(kMainWindowStateKey, QVariant::fromValue(mainWindowState));
+    result.insert(kHeaderViewStatesKey, QVariant::fromValue(headerViewStates));
+    return result;
+}
+PerspectiveState PerspectiveState::fromSettings(const Store &settings)
+{
+    PerspectiveState state;
+    state.mainWindowState = settings.value(kMainWindowStateKey).value<Store>();
+    state.headerViewStates = settings.value(kHeaderViewStatesKey).value<QVariantHash>();
+    return state;
+}
+
 } // Utils
diff --git a/src/plugins/debugger/debuggermainwindow.h b/src/plugins/debugger/debuggermainwindow.h
index fbe959f19fd..ed53e30db78 100644
--- a/src/plugins/debugger/debuggermainwindow.h
+++ b/src/plugins/debugger/debuggermainwindow.h
@@ -7,6 +7,7 @@
 
 #include <utils/fancymainwindow.h>
 #include <utils/statuslabel.h>
+#include <utils/storekey.h>
 
 #include <QAction>
 #include <QPointer>
@@ -37,13 +38,27 @@ class PerspectiveState
 public:
     static const char *savesHeaderKey();
 
-    QByteArray mainWindowState;
+    bool hasWindowState() const;
+
+    bool restoreWindowState(FancyMainWindow *mainWindow);
+
+    Store mainWindowState;
     QVariantHash headerViewStates;
 
+    QByteArray mainWindowStateLegacy; // legacy for up to QtC 12
+
+    Store toSettings() const;
+    static PerspectiveState fromSettings(const Store &settings);
+
+    // legacy for up to QtC 12, operators for direct QVariant conversion
     friend QDataStream &operator>>(QDataStream &ds, PerspectiveState &state)
-        { return ds >> state.mainWindowState >> state.headerViewStates; }
+    {
+        return ds >> state.mainWindowStateLegacy >> state.headerViewStates;
+    }
     friend QDataStream &operator<<(QDataStream &ds, const PerspectiveState &state)
-        { return ds << state.mainWindowState << state.headerViewStates; }
+    {
+        return ds << state.mainWindowStateLegacy << state.headerViewStates;
+    }
 };
 
 class DEBUGGER_EXPORT Perspective : public QObject
diff --git a/src/plugins/debugger/debuggerplugin.cpp b/src/plugins/debugger/debuggerplugin.cpp
index cbfe4b7b2b6..1a5b9ad21e4 100644
--- a/src/plugins/debugger/debuggerplugin.cpp
+++ b/src/plugins/debugger/debuggerplugin.cpp
@@ -512,6 +512,7 @@ public:
         mainWindow->addSubPerspectiveSwitcher(EngineManager::dapEngineChooser());
 
         setWidget(splitter);
+        setMainWindow(mainWindow);
 
         setMenu(DebuggerMainWindow::perspectiveMenu());
     }