diff --git a/YACReaderLibrary/library_window.cpp b/YACReaderLibrary/library_window.cpp
index 62bd5855..4290de4c 100644
--- a/YACReaderLibrary/library_window.cpp
+++ b/YACReaderLibrary/library_window.cpp
@@ -22,6 +22,8 @@
 
 #include <iterator>
 #include <typeinfo>
+#include <thread>
+#include <future>
 
 #include "data_base_management.h"
 #include "yacreader_global.h"
@@ -1113,6 +1115,15 @@ void LibraryWindow::createConnections()
 
     //save covers
     connect(saveCoversToAction,SIGNAL(triggered()),this,SLOT(saveSelectedCoversTo()));
+
+    //upgrade library
+    connect(this, SIGNAL(libraryUpgraded(QString)), this, SLOT(loadLibrary(QString)), Qt::QueuedConnection);
+    connect(this, SIGNAL(errorUpgradingLibrary(QString)), this, SLOT(showErrorUpgradingLibrary(QString)), Qt::QueuedConnection);
+}
+
+void LibraryWindow::showErrorUpgradingLibrary(const QString & path)
+{
+    QMessageBox::critical(this,tr("Upgrade failed"), tr("There were errors during library upgrade in: ") + path+"/library.ydb");
 }
 
 void LibraryWindow::loadLibrary(const QString & name)
@@ -1128,29 +1139,39 @@ void LibraryWindow::loadLibrary(const QString & name)
 		if(d.exists(path) && d.exists(path+"/library.ydb") && (dbVersion = DataBaseManagement::checkValidDB(path+"/library.ydb")) != "") //si existe en disco la biblioteca seleccionada, y es válida..
 		{
 			int comparation = DataBaseManagement::compareVersions(dbVersion,VERSION);
-			bool updated = false;
-			if(comparation < 0)
-				{
-					int ret = QMessageBox::question(this,tr("Update needed"),tr("This library was created with a previous version of YACReaderLibrary. It needs to be updated. Update now?"),QMessageBox::Yes,QMessageBox::No);
-					if(ret == QMessageBox::Yes)
-					{
-						updated = DataBaseManagement::updateToCurrentVersion(path+"/library.ydb");
-						if(!updated)
-							QMessageBox::critical(this,tr("Update failed"), tr("The current library can't be udpated. Check for write write permissions on: ") + path+"/library.ydb");
-					}
-					else
-                    {
-                        comicsViewsManager->comicsView->setModel(NULL);
-						foldersView->setModel(NULL);
-                        listsView->setModel(NULL);
-						disableAllActions();//TODO comprobar que se deben deshabilitar
-						//será possible renombrar y borrar estas bibliotecas
-						renameLibraryAction->setEnabled(true);
-						removeLibraryAction->setEnabled(true);
-					}
-				}
 
-			if(comparation == 0 || updated) //en caso de que la versión se igual que la actual
+            if(comparation < 0)
+            {
+                int ret = QMessageBox::question(this,tr("Update needed"),tr("This library was created with a previous version of YACReaderLibrary. It needs to be updated. Update now?"),QMessageBox::Yes,QMessageBox::No);
+                if(ret == QMessageBox::Yes)
+                {
+                    importWidget->setUpgradeLook();
+                    showImportingWidget();
+
+                    upgradeLibraryFuture = std::async(std::launch::async, [this, name, path] {
+                        bool updated = DataBaseManagement::updateToCurrentVersion(path);
+
+                        if(!updated)
+                            emit errorUpgradingLibrary(path);
+
+                        emit libraryUpgraded(name);
+                    });
+
+                    return;
+                }
+                else
+                {
+                    comicsViewsManager->comicsView->setModel(NULL);
+                    foldersView->setModel(NULL);
+                    listsView->setModel(NULL);
+                    disableAllActions();//TODO comprobar que se deben deshabilitar
+                    //será possible renombrar y borrar estas bibliotecas
+                    renameLibraryAction->setEnabled(true);
+                    removeLibraryAction->setEnabled(true);
+                }
+            }
+
+            if(comparation == 0) //en caso de que la versión se igual que la actual
 			{
                 foldersModel->setupModelData(path);
                 foldersModelProxy->setSourceModel(foldersModel);
diff --git a/YACReaderLibrary/library_window.h b/YACReaderLibrary/library_window.h
index 98796e1a..0365e51b 100644
--- a/YACReaderLibrary/library_window.h
+++ b/YACReaderLibrary/library_window.h
@@ -10,6 +10,8 @@
 
 #include "yacreader_navigation_controller.h"
 
+#include <future>
+
 #ifdef Q_OS_MAC
     #include "yacreader_macosx_toolbar.h"
 #endif
@@ -284,6 +286,9 @@ protected:
 public:
     LibraryWindow();
 
+signals:
+    void libraryUpgraded(const QString & libraryName);
+    void errorUpgradingLibrary(const QString & path);
 public slots:
     void loadLibrary(const QString & path);
     void selectSubfolder(const QModelIndex & mi, int child);
@@ -376,12 +381,15 @@ public slots:
     void setToolbarTitle(const QModelIndex & modelIndex);
     void saveSelectedCoversTo();
     void checkMaxNumLibraries();
+    void showErrorUpgradingLibrary(const QString & path);
 
 private:
     //fullscreen mode in Windows for preventing this bug: QTBUG-41309 https://bugreports.qt.io/browse/QTBUG-41309
     Qt::WindowFlags previousWindowFlags;
     QPoint previousPos;
     QSize previousSize;
+
+    std::future<void> upgradeLibraryFuture;
 };
 
 #endif