diff --git a/kded/serializer.cpp b/kded/serializer.cpp
--- a/kded/serializer.cpp
+++ b/kded/serializer.cpp
@@ -55,6 +55,9 @@
 
 QString Serializer::configId(const KScreen::ConfigPtr &currentConfig)
 {
+    if (!currentConfig) {
+        return QString();
+    }
     KScreen::OutputList outputs = currentConfig->outputs();
 
     QStringList hashList;
@@ -92,6 +95,7 @@
 
     QFile file(configFileName(id));
     if (!file.open(QIODevice::ReadOnly)) {
+        qCDebug(KSCREEN_KDED) << "failed to open file" << id;
         return KScreen::ConfigPtr();
     }
 
@@ -136,6 +140,9 @@
 
 bool Serializer::saveConfig(const KScreen::ConfigPtr &config, const QString &configId)
 {
+    if (!config || configId.isEmpty()) {
+        return false;
+    }
     const KScreen::OutputList outputs = config->outputs();
 
     QVariantList outputList;
diff --git a/tests/kded/serializertest.cpp b/tests/kded/serializertest.cpp
--- a/tests/kded/serializertest.cpp
+++ b/tests/kded/serializertest.cpp
@@ -43,6 +43,7 @@
     void testCorruptConfig();
     void testCorruptEmptyConfig();
     void testCorruptUselessConfig();
+    void testNullConfig();
 
 private:
     KScreen::ConfigPtr createConfig(bool output1Connected, bool output2Conected);
@@ -240,6 +241,22 @@
     QVERIFY(config->isValid());
 }
 
+void TestSerializer::testNullConfig()
+{
+    KScreen::ConfigPtr nullConfig;
+    QVERIFY(!nullConfig);
+
+    // Null configs have empty configIds
+    QVERIFY(Serializer::configId(nullConfig).isEmpty());
+
+    // Load config from a file not found results in a nullptr
+    KScreen::ConfigPtr config = createConfig(true, true);
+    QVERIFY(!Serializer::config(config, QString()));
+
+    // Wrong config file name should fail to save
+    QCOMPARE(Serializer::saveConfig(config, QString()), false);
+}
+
 QTEST_MAIN(TestSerializer)
 
 #include "serializertest.moc"
\ No newline at end of file