Index: NetworkEditor/src/MainWindow.hxx
===================================================================
--- NetworkEditor/src/MainWindow.hxx	(revision 14445)
+++ NetworkEditor/src/MainWindow.hxx	(working copy)
@@ -19,10 +19,7 @@
 #include <CLAM/CLAMVersion.hxx>
 #include "NetworkEditorVersion.hxx"
 #include "RichTextEditor.hxx"
-//#include <CLAM/EmbeddedFile.hxx>
-//CLAM_EMBEDDED_FILE(genderChange,"PluginExamples/ClamLadspaPluginExample/genderChange.clamnetwork")
 
-
 // copied from Annotator:
 #include "TaskRunner.hxx"
 
@@ -50,7 +47,21 @@
 
 #include <QtXmlPatterns/QXmlQuery>
 #include <QtCore/QStringList>
+#include "Python.h"
+#include <fstream>
+#include <CLAM/EmbeddedFile.hxx>
+CLAM_EMBEDDED_FILE(migrationScript,"migrationScript")
 
+class ClamrefactorException : public std::exception {
+public:
+	ClamrefactorException(char * msg) : _msg(msg) {}
+	const char * what() const throw () {
+		return _msg;
+	}
+private:
+	char * _msg;
+};
+
 //#define AFTER13RELEASE
 
 class PlaybackIndicator : public QLabel
@@ -265,13 +276,9 @@
 			return;
 		}
 		int comparison = compareVersions(networkVersion, CLAM::GetVersion());
-
-		// Fake to disable upgrades while they depend on file locations
-		if (comparison==-1) comparison=0;
-
-		if (comparison==-1) // Older version
+		if (comparison==-1)
 		{
-			int response = QMessageBox::warning(this,
+			QMessageBox::warning(this,
 				tr("NetworkEditor"),
 				tr("This network was created with an older version, %1, of NetworkEditor.\n"
 				"It will be updated to version %2 when saved.")
@@ -279,17 +286,25 @@
 					.arg(CLAM::GetVersion())
 					,
 				QMessageBox::Ok);
-			const char * translatedNetwork = updatedNetworkVersion(qPrintable(filename));
-			if (translatedNetwork)
-			{
-				loadFromString(translatedNetwork, filename);
+			try {
+				const char * translatedNetwork = updatedNetworkVersion(qPrintable(filename));
+				if (translatedNetwork)
+				{
+					loadFromString(translatedNetwork, filename);
+					return;
+				}
+			}
+			catch(ClamrefactorException & e) {
+				QMessageBox::warning(this,
+				tr("NetworkEditor"),
+				tr(qPrintable(QString("An error ocurred while updating the network:\n") +
+				e.what()))
+				,
+				QMessageBox::Ok);
 				return;
 			}
-			QMessageBox::warning(this,
-				tr("NetworkEditor"),
-				tr("Updating procedure failed, trying to load old version file."));
 		}
-		if (comparison==+1) // Newer version
+		if (comparison==+1)
 		{
 			int response = QMessageBox::question(this,
 				tr("NetworkEditor"),
@@ -304,7 +319,78 @@
 		}
 		loadFromFile(filename);
 	}
-	const char * updatedNetworkVersion(const std::string & filename);
+	void getExceptionMessage()
+	{
+		PyObject *pType, *pValue, *pTrace;
+		PyErr_Fetch(&pType, &pValue, &pTrace);
+		char *strErrorMessage = PyString_AsString(pValue);
+		throw(ClamrefactorException(strErrorMessage));
+	}
+	const char * updatedNetworkVersion(const std::string & filename)
+	{
+		Py_Initialize();
+		PyObject * pModule = PyImport_ImportModule("clamrefactor");
+		if (pModule == NULL)
+		{
+			getExceptionMessage();
+		}
+		PyObject * pDict = PyModule_GetDict(pModule);
+		// Build the name of a callable class 
+		PyObject * pClassClamNetwork = PyDict_GetItemString(pDict, "ClamNetwork");
+		// Create an instance of the class
+		if (!PyCallable_Check(pClassClamNetwork))
+		{
+			getExceptionMessage();
+		}
+		PyObject * pClamNetwork = Py_BuildValue( "(s)", filename.c_str() );
+		PyObject * pInstanceClamNetwork = PyObject_CallObject(pClassClamNetwork, pClamNetwork); 
+		Py_DECREF(pClamNetwork);
+		if (pInstanceClamNetwork == NULL)
+		{
+			getExceptionMessage();
+		}
+		std::stringstream ss(migrationScript);
+		std::string command;
+		PyObject * pValue;
+		while( std::getline(ss, command) )
+		{
+			pValue = PyObject_CallMethod( pInstanceClamNetwork, "runCommand", "(s)", command.c_str() );
+		}
+
+		PyObject * pModule2 = PyImport_ImportModule("StringIO");
+		if (pModule2 == NULL)
+		{
+			getExceptionMessage();
+			return 0;
+		}
+		PyObject * pDict2 = PyModule_GetDict(pModule2);
+		PyObject * pClassStringIO = PyDict_GetItemString(pDict2, "StringIO");
+		PyObject * pStringIO = Py_BuildValue( "(s)", "" );
+		PyObject * pInstanceStringIO = PyObject_CallObject(pClassStringIO, pStringIO);
+		if (!PyCallable_Check(pClassStringIO))
+		{
+			getExceptionMessage(); 
+		}
+		PyObject_CallMethod(pInstanceClamNetwork, "dump", "(O)", pInstanceStringIO);
+		pValue = PyObject_CallMethod(pInstanceStringIO, "getvalue", NULL);
+
+		char * cstring;
+		if (pValue == NULL)
+		{
+			getExceptionMessage();
+		}
+
+		PyArg_Parse(pValue, "s", &cstring);
+		Py_DECREF(pModule);
+		Py_DECREF(pModule2);
+		Py_DECREF(pStringIO);
+		Py_DECREF(pInstanceClamNetwork);
+		Py_DECREF(pInstanceStringIO);
+		Py_DECREF(pValue);
+		Py_Finalize();
+
+		return cstring;
+	}
 	void loadFromFile(const QString & filename)
 	{
 		_network.ResetConnectionReport();
@@ -342,7 +428,7 @@
 		_networkFile = filename;
 		updateCaption();
 	}
-	void loadFromString(const char *strNetwork, const QString & filename)
+	void loadFromString(const char * strNetwork, const QString & filename)
 	{
 		_network.ResetConnectionReport();
 
Index: NetworkEditor/src/MainWindow.cxx
===================================================================
--- NetworkEditor/src/MainWindow.cxx	(revision 14445)
+++ NetworkEditor/src/MainWindow.cxx	(working copy)
@@ -1,8 +1,6 @@
 #include <QtCore/QTemporaryFile>
 #include "ui_LadspaMetadataEditor.hxx"
 #include "LadspaPluginCompilationTask.hxx"
-#include "Python.h"
-#include <fstream>
 
 MainWindow::~MainWindow()
 {
@@ -102,78 +100,3 @@
 		_processingTree->RePopulateTree();
 #endif
 }
-
-
-//CLAM_EMBEDEDFILE(migrationScript, "migrationScript");
-
-const char * MainWindow::updatedNetworkVersion(const std::string & filename)
-{
-	Py_Initialize();
-	PyObject * pModule = PyImport_ImportModule("clamrefactor");
-	if (pModule == NULL)
-	{
-		PyErr_Print();
-		return 0;
-	}
-	PyObject * pDict = PyModule_GetDict(pModule);
-	// Build the name of a callable class 
-	PyObject * pClassClamNetwork = PyDict_GetItemString(pDict, "ClamNetwork");
-	// Create an instance of the class
-	if (! PyCallable_Check(pClassClamNetwork))
-	{
-		//TODO Manage error
-		return 0;
-	}
-	PyObject * pClamNetwork = Py_BuildValue( "(s)", filename.c_str() );
-	PyObject * pInstanceClamNetwork = PyObject_CallObject(pClassClamNetwork, pClamNetwork); 
-	Py_DECREF(pClamNetwork);
-
-	if (pInstanceClamNetwork == NULL)
-	{
-		PyErr_Print();
-		return 0;
-	}
-	std::ifstream ifs( "migrationScript" );
-	std::string command;
-	PyObject *pValue;
-	while( getline(ifs, command) )
-	{
-		pValue = PyObject_CallMethod( pInstanceClamNetwork, "runCommand", "(s)", command.c_str() );
-	}
-
-	PyObject *pModule2, *pDict2, *pClassStringIO, *pStringIO, *pInstanceStringIO;
-	pModule2 = PyImport_ImportModule("StringIO");
-	if (pModule2 == NULL)
-	{
-		PyErr_Print();
-		return 0;
-	}
-	pDict2 = PyModule_GetDict(pModule2);
-	pClassStringIO = PyDict_GetItemString(pDict2, "StringIO");
-	if (PyCallable_Check(pClassStringIO))
-	{
-		pStringIO = Py_BuildValue( "(s)", "" );
-		pInstanceStringIO = PyObject_CallObject(pClassStringIO, pStringIO); 
-	}
-
-	PyObject_CallMethod(pInstanceClamNetwork, "dump", "(O)", pInstanceStringIO);
-	pValue = PyObject_CallMethod(pInstanceStringIO, "getvalue", NULL);
-
-	char *cstring;
-	if (pValue == NULL)
-	{
-		PyErr_Print();
-		return 0;
-	}
-
-	PyArg_Parse(pValue, "s", &cstring);
-	Py_DECREF(pModule);
-	Py_DECREF(pModule2);
-	Py_DECREF(pStringIO);
-	Py_DECREF(pInstanceClamNetwork);
-	Py_DECREF(pInstanceStringIO);
-	Py_DECREF(pValue);
-	Py_Finalize();
-
-	return cstring;
-}