diff --git a/src/plugins/coreplugin/locator/directoryfilter.cpp b/src/plugins/coreplugin/locator/directoryfilter.cpp
index 871e89753e6..38eac7efd0a 100644
--- a/src/plugins/coreplugin/locator/directoryfilter.cpp
+++ b/src/plugins/coreplugin/locator/directoryfilter.cpp
@@ -150,42 +150,6 @@ void DirectoryFilter::restoreState(const QJsonObject &object)
             .toArray(QJsonArray::fromStringList(kExclusionFiltersDefault)));
 }
 
-void DirectoryFilter::restoreState(const QByteArray &state)
-{
-    if (isOldSetting(state)) {
-        // TODO read old settings, remove some time after Qt Creator 4.15
-        QString name;
-        QStringList directories;
-        QString shortcut;
-        bool defaultFilter;
-        QStringList files;
-
-        QDataStream in(state);
-        in >> name;
-        in >> directories;
-        in >> m_filters;
-        in >> shortcut;
-        in >> defaultFilter;
-        in >> files;
-        m_cache.setFilePaths(FileUtils::toFilePathList(files));
-        if (!in.atEnd()) // Qt Creator 4.3 and later
-            in >> m_exclusionFilters;
-        else
-            m_exclusionFilters.clear();
-
-        if (m_isCustomFilter) {
-            m_directories = Utils::transform(directories, [](const QString &d) {
-                return FilePath::fromString(d);
-            });
-        }
-        setDisplayName(name);
-        setShortcutString(shortcut);
-        setIncludedByDefault(defaultFilter);
-    } else {
-        ILocatorFilter::restoreState(state);
-    }
-}
-
 class DirectoryFilterOptions : public QDialog
 {
 public:
diff --git a/src/plugins/coreplugin/locator/directoryfilter.h b/src/plugins/coreplugin/locator/directoryfilter.h
index 452a1b20e75..8300d03d464 100644
--- a/src/plugins/coreplugin/locator/directoryfilter.h
+++ b/src/plugins/coreplugin/locator/directoryfilter.h
@@ -12,7 +12,6 @@ class CORE_EXPORT DirectoryFilter : public ILocatorFilter
 {
 public:
     DirectoryFilter(Utils::Id id);
-    void restoreState(const QByteArray &state) override;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) override;
 
 protected:
diff --git a/src/plugins/coreplugin/locator/filesystemfilter.cpp b/src/plugins/coreplugin/locator/filesystemfilter.cpp
index 00890829b45..f108382d708 100644
--- a/src/plugins/coreplugin/locator/filesystemfilter.cpp
+++ b/src/plugins/coreplugin/locator/filesystemfilter.cpp
@@ -392,25 +392,4 @@ void FileSystemFilter::restoreState(const QJsonObject &object)
     m_includeHidden = object.value(kIncludeHiddenKey).toBool(s_includeHiddenDefault);
 }
 
-void FileSystemFilter::restoreState(const QByteArray &state)
-{
-    if (isOldSetting(state)) {
-        // TODO read old settings, remove some time after Qt Creator 4.15
-        QDataStream in(state);
-        in >> m_includeHidden;
-
-        // An attempt to prevent setting this on old configuration
-        if (!in.atEnd()) {
-            QString shortcut;
-            bool defaultFilter;
-            in >> shortcut;
-            in >> defaultFilter;
-            setShortcutString(shortcut);
-            setIncludedByDefault(defaultFilter);
-        }
-    } else {
-        ILocatorFilter::restoreState(state);
-    }
-}
-
 } // namespace Core::Internal
diff --git a/src/plugins/coreplugin/locator/filesystemfilter.h b/src/plugins/coreplugin/locator/filesystemfilter.h
index 3dfac11b3a5..74198ec9aea 100644
--- a/src/plugins/coreplugin/locator/filesystemfilter.h
+++ b/src/plugins/coreplugin/locator/filesystemfilter.h
@@ -11,7 +11,6 @@ class FileSystemFilter : public ILocatorFilter
 {
 public:
     FileSystemFilter();
-    void restoreState(const QByteArray &state) final;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) final;
 
 protected:
diff --git a/src/plugins/coreplugin/locator/ilocatorfilter.cpp b/src/plugins/coreplugin/locator/ilocatorfilter.cpp
index e9a999d536d..4b012f6398f 100644
--- a/src/plugins/coreplugin/locator/ilocatorfilter.cpp
+++ b/src/plugins/coreplugin/locator/ilocatorfilter.cpp
@@ -671,15 +671,6 @@ void ILocatorFilter::restoreState(const QByteArray &state)
         setShortcutString(obj.value(kShortcutStringKey).toString(m_defaultShortcut));
         setIncludedByDefault(obj.value(kIncludedByDefaultKey).toBool(m_defaultIncludedByDefault));
         restoreState(obj);
-    } else {
-        // TODO read old settings, remove some time after Qt Creator 4.15
-        m_shortcut = m_defaultShortcut;
-        m_includedByDefault = m_defaultIncludedByDefault;
-
-        // TODO this reads legacy settings from Qt Creator < 4.15
-        QDataStream in(state);
-        in >> m_shortcut;
-        in >> m_includedByDefault;
     }
 }
 
@@ -1060,17 +1051,6 @@ void ILocatorFilter::restoreState(const QJsonObject &object)
     Q_UNUSED(object)
 }
 
-/*!
-    Returns if \a state must be restored via pre-4.15 settings reading.
-*/
-bool ILocatorFilter::isOldSetting(const QByteArray &state)
-{
-    if (state.isEmpty())
-        return false;
-    const QJsonDocument doc = QJsonDocument::fromJson(state);
-    return !doc.isObject();
-}
-
 /*!
     \enum Core::ILocatorFilter::Priority
 
diff --git a/src/plugins/coreplugin/locator/ilocatorfilter.h b/src/plugins/coreplugin/locator/ilocatorfilter.h
index 4a4bcc5c0e3..368f0313814 100644
--- a/src/plugins/coreplugin/locator/ilocatorfilter.h
+++ b/src/plugins/coreplugin/locator/ilocatorfilter.h
@@ -226,8 +226,8 @@ public:
     std::optional<QString> defaultSearchText() const;
     void setDefaultSearchText(const QString &defaultSearchText);
 
-    virtual QByteArray saveState() const;
-    virtual void restoreState(const QByteArray &state);
+    QByteArray saveState() const;
+    void restoreState(const QByteArray &state);
 
     virtual bool openConfigDialog(QWidget *parent, bool &needsRefresh);
     bool isConfigurable() const;
@@ -272,8 +272,6 @@ protected:
     void setRefreshRecipe(const std::optional<Tasking::GroupItem> &recipe);
     std::optional<Tasking::GroupItem> refreshRecipe() const;
 
-    static bool isOldSetting(const QByteArray &state);
-
 private:
     virtual LocatorMatcherTasks matchers() = 0;
 
diff --git a/src/plugins/coreplugin/locator/urllocatorfilter.cpp b/src/plugins/coreplugin/locator/urllocatorfilter.cpp
index 1c67d9e0328..7457f0907cc 100644
--- a/src/plugins/coreplugin/locator/urllocatorfilter.cpp
+++ b/src/plugins/coreplugin/locator/urllocatorfilter.cpp
@@ -207,34 +207,6 @@ void UrlLocatorFilter::restoreState(const QJsonObject &object)
                                     &QVariant::toString);
 }
 
-void UrlLocatorFilter::restoreState(const QByteArray &state)
-{
-    if (isOldSetting(state)) {
-        // TODO read old settings, remove some time after Qt Creator 4.15
-        QDataStream in(state);
-
-        QString value;
-        in >> value;
-        m_remoteUrls = value.split('^', Qt::SkipEmptyParts);
-
-        QString shortcut;
-        in >> shortcut;
-        setShortcutString(shortcut);
-
-        bool defaultFilter;
-        in >> defaultFilter;
-        setIncludedByDefault(defaultFilter);
-
-        if (!in.atEnd()) {
-            QString name;
-            in >> name;
-            setDisplayName(name);
-        }
-    } else {
-        ILocatorFilter::restoreState(state);
-    }
-}
-
 bool UrlLocatorFilter::openConfigDialog(QWidget *parent, bool &needsRefresh)
 {
     Q_UNUSED(needsRefresh)
diff --git a/src/plugins/coreplugin/locator/urllocatorfilter.h b/src/plugins/coreplugin/locator/urllocatorfilter.h
index 18535569c5b..cc579034792 100644
--- a/src/plugins/coreplugin/locator/urllocatorfilter.h
+++ b/src/plugins/coreplugin/locator/urllocatorfilter.h
@@ -24,7 +24,6 @@ public:
     UrlLocatorFilter(Utils::Id id);
     UrlLocatorFilter(const QString &displayName, Utils::Id id);
 
-    void restoreState(const QByteArray &state) final;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) final;
 
     void addDefaultUrl(const QString &urlTemplate);