diff --git a/source/DataModel.cpp b/source/DataModel.cpp
index eba7f53..eef2e2f 100644
--- a/source/DataModel.cpp
+++ b/source/DataModel.cpp
@@ -46,7 +46,7 @@ void DataModel::write(const QString &filename) const
 	QFile outFile(filename);
 	if (!outFile.open(QIODevice::WriteOnly))
 	{
-		return;
+		throw std::runtime_error("open failed");
 	}
 
 	dataModel.SerializeToFileDescriptor(outFile.handle());
@@ -57,7 +57,7 @@ void DataModel::read(const QString &filename)
 	QFile inFile(filename);
 	if (!inFile.open(QIODevice::ReadOnly))
 	{
-		return;
+		throw std::runtime_error("open failed");
 	}
 
 	ESGRAF48::DataModel dataModel;
diff --git a/source/mainwindow.cpp b/source/mainwindow.cpp
index 8f0eab0..aa6a915 100644
--- a/source/mainwindow.cpp
+++ b/source/mainwindow.cpp
@@ -85,7 +85,15 @@ void MainWindow::openFile()
 		return;
 	}
 
-	openFile(filename);
+	try
+	{
+		openFile(filename);
+	}
+	catch (std::exception &e)
+	{
+		QString errorMessage = QString("Error loading \"") + filename + "\": " + e.what();
+		QMessageBox::critical(this, "Error", errorMessage);
+	}
 }
 
 void MainWindow::openFile(const QString &filename)
@@ -195,7 +203,16 @@ void MainWindow::closeEvent(QCloseEvent *event)
 
 void MainWindow::saveFile(const QString &filename)
 {
-	m_dataModel.write(filename);
+	try
+	{
+		m_dataModel.write(filename);
+	}
+	catch (std::exception &e)
+	{
+		QString errorMessage = QString("Error saving \"") + filename + "\": " + e.what();
+		QMessageBox::critical(this, "Error", errorMessage);
+		return;
+	}
 
 	qDebug() << "Wrote" << filename;