diff --git a/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.cpp b/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.cpp
index e56e6abe0c..94df23e9f0 100644
--- a/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.cpp
+++ b/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.cpp
@@ -1,172 +1,184 @@
 /* ============================================================
  *
  * This file is a part of digiKam project
  * https://www.digikam.org
  *
  * Date        : 2011-03-22
  * Description : a MediaWiki C++ interface
  *
  * Copyright (C) 2011-2019 by Gilles Caulier <caulier dot gilles at gmail dot com>
  * Copyright (C) 2011      by Alexandre Mendes <alex dot mendes1988 at gmail dot com>
  * Copyright (C) 2011      by Hormiere Guillaume <hormiere dot guillaume at gmail dot com>
  * Copyright (C) 2011      by Manuel Campomanes <campomanes dot manuel at gmail dot com>
  *
  * This program is free software; you can redistribute it
  * and/or modify it under the terms of the GNU General
  * Public License as published by the Free Software Foundation;
  * either version 2, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
  * ============================================================ */
 
 #include "mainwindow.h"
 #include "ui_mainwindow.h"
 
 // Qt includes
 
 #include <QFile>
 #include <QFileDialog>
 
 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent),
       ui(new Ui::MainWindow),
       MediaWiki(QUrl(QLatin1String("https://test.wikipedia.org/w/api.php")))
 {
     ui->setupUi(this);
     init();
 }
 
 MainWindow::~MainWindow()
 {
     delete ui;
 }
 
 void MainWindow::init()
 {
     this->ui->comboBox->addItem(QLatin1String("Own work, multi-license with CC-BY-SA-3.0 and GFDL"),                        QLatin1String("{{self|cc-by-sa-3.0|GFDL|migration=redundant}}"));
     this->ui->comboBox->addItem(QLatin1String("Own work, multi-license with CC-BY-SA-3.0 and older"),                       QLatin1String("{{self|cc-by-sa-3.0,2.5,2.0,1.0}}"));
     this->ui->comboBox->addItem(QLatin1String("Creative Commons Attribution-Share Alike 3.0"),                              QLatin1String("{{self|cc-by-sa-3.0}}"));
     this->ui->comboBox->addItem(QLatin1String("Own work, Creative Commons Attribution 3.0"),                                QLatin1String("{{self|cc-by-3.0}}"));
     this->ui->comboBox->addItem(QLatin1String("Own work, release into public domain under the CC-Zero license"),            QLatin1String("{{self|cc-zero}}"));
     this->ui->comboBox->addItem(QLatin1String("Author died more than 100 years ago"),                                       QLatin1String("{{PD-old}}"));
     this->ui->comboBox->addItem(QLatin1String("Photo of a two-dimensional work whose author died more than 100 years ago"), QLatin1String("{{PD-art}}"));
     this->ui->comboBox->addItem(QLatin1String("First published in the United States before 1923"),                          QLatin1String("{{PD-US}}"));
     this->ui->comboBox->addItem(QLatin1String("Work of a U.S. government agency"),                                          QLatin1String("{{PD-USGov}}"));
     this->ui->comboBox->addItem(QLatin1String("Simple typefaces, individual words or geometric shapes"),                    QLatin1String("{{PD-text}}"));
     this->ui->comboBox->addItem(QLatin1String("Logos with only simple typefaces, individual words or geometric shapes"),    QLatin1String("{{PD-textlogo}}"));
 }
 
 void MainWindow::on_pushButton_clicked()
 {
     this->ui->progressBar->setValue(0);
     Login* const login = new Login(MediaWiki, this->ui->mLoginEdit->text(), this->ui->mMdpEdit->text());
 
     connect(login, SIGNAL(result(KJob*)),
             this, SLOT(loginHandle(KJob*)));
 
     login->start();
 }
 
 void MainWindow::loginHandle(KJob* login)
 {
     if (login->error() != 0)
     {
         QMessageBox popup;
         popup.setText(QLatin1String("Wrong authentication."));
         popup.exec();
     }
     else
     {
         Upload* const e1  = new Upload( MediaWiki );
         QFile* const file = new QFile(this->ui->lineEdit->text());
-        file->open(QIODevice::ReadOnly);
+
+        if (!file->open(QIODevice::ReadOnly))
+        {
+            QMessageBox popup;
+            popup.setText(QString::fromLatin1("Cannot open file %1.").arg(this->ui->lineEdit->text()));
+            popup.exec();
+            return;
+        }
+
         e1->setFile(file);
         e1->setFilename(this->ui->lineEdit_2->text());
 
         QString text = QLatin1String("== {{int:filedesc}} == \n{{Information |Description=");
         text.append(this->ui->descriptionEdit->text());
         text.append(QLatin1String("\n|Source=")).append(this->ui->sourceEdit->text());
         text.append(QLatin1String("\n|Date=")).append(this->ui->dateEdit->text());
         text.append(QLatin1String("\n|Author=")).append(this->ui->authorEdit->text());
         text.append(QLatin1String("\n|Permission=")).append(this->ui->permissionEdit->text());
         text.append(QLatin1String("\n|other_versions=")).append(this->ui->versionsEdit->text());
         text.append(QLatin1String("\n}}\n== {{int:license}} ==\n"));
         text.append(this->ui->comboBox->itemData(this->ui->comboBox->currentIndex()).toString());
 
         e1->setText(text);
 
         connect(e1, SIGNAL(result(KJob*)),
                 this, SLOT(uploadHandle(KJob*)));
 
         connect(e1,SIGNAL(processedSize(KJob*,qulonglong)),
                 this, SLOT(processedUploadSize(KJob*,qulonglong)));
 
         connect(e1,SIGNAL(totalSize(KJob*,qulonglong)),
                 this,SLOT(TotalUploadSize(KJob*,qulonglong)));
 
         e1->start();
     }
 }
 
 void MainWindow::uploadHandle(KJob* job)
 {
     disconnect(this, SIGNAL(result(KJob*)),
                this, SLOT(uploadHandle(KJob*)));
 
     disconnect(this, SIGNAL(processedSize(KJob*,qulonglong)),
                this, SLOT(processedUploadSize(KJob*,qulonglong)));
 
     disconnect(this, SIGNAL(totalSize(KJob*,qulonglong)),
                this, SLOT(TotalUploadSize(KJob*,qulonglong)));
 
     QString errorMessage;
 
     if (job->error() == 0)
+    {
         errorMessage = QLatin1String("Image uploaded successfully.");
+    }
     else
+    {
         errorMessage = QLatin1String("Image upload failed.");
+    }
 
     QMessageBox popup;
     popup.setText(errorMessage);
     popup.exec();
 }
 
 void MainWindow::processedUploadSize(KJob* job, qulonglong size)
 {
     Q_UNUSED(job)
     this->ui->progressBar->setValue(size);
 }
 
 void MainWindow::TotalUploadSize(KJob* job, qulonglong size)
 {
     Q_UNUSED(job)
     this->ui->progressBar->setMaximum(size);
 }
 
 void MainWindow::on_parcourir_clicked()
 {
     QString fileName = QFileDialog::getOpenFileName(this,
                                                     QLatin1String("Open Image"),
                                                     QLatin1String("~"),
                                                     QLatin1String("Image Files (*.png *.jpg *.bmp *.jpeg *.gif)"));
 
     if (!fileName.isEmpty())
     {
         QPixmap preview(fileName);
         QSize size(preview.size());
         size.scale(400, 200, Qt::KeepAspectRatio);
         preview = preview.scaled(size, Qt::KeepAspectRatio, Qt::FastTransformation);
 
         this->ui->previewLabel->setPixmap(preview);
         this->ui->lineEdit->setText(fileName);
     }
 }
 
-void MainWindow::on_lineEdit_textChanged(QString text)
+void MainWindow::on_lineEdit_textChanged(const QString& text)
 {
     this->ui->pushButton->setEnabled(!text.isEmpty() && !text.isNull());
 }
diff --git a/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.h b/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.h
index 9c4d98d582..fbb9123ba3 100644
--- a/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.h
+++ b/core/dplugins/generic/webservices/mediawiki/tests/examples/uploadsample/mainwindow.h
@@ -1,78 +1,78 @@
 /* ============================================================
  *
  * This file is a part of digiKam project
  * https://www.digikam.org
  *
  * Date        : 2011-03-22
  * Description : a MediaWiki C++ interface
  *
  * Copyright (C) 2011-2019 by Gilles Caulier <caulier dot gilles at gmail dot com>
  * Copyright (C) 2011      by Alexandre Mendes <alex dot mendes1988 at gmail dot com>
  * Copyright (C) 2011      by Hormiere Guillaume <hormiere dot guillaume at gmail dot com>
  * Copyright (C) 2011      by Manuel Campomanes <campomanes dot manuel at gmail dot com>
  *
  * This program is free software; you can redistribute it
  * and/or modify it under the terms of the GNU General
  * Public License as published by the Free Software Foundation;
  * either version 2, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
  * ============================================================ */
 
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
 // Qt includes
 
 #include <QMainWindow>
 #include <QMessageBox>
 
 // Local includes
 
 #include "mediawiki_upload.h"
 #include "mediawiki_iface.h"
 #include "mediawiki_login.h"
 #include "mediawiki_queryinfo.h"
 #include "mediawiki_queryrevision.h"
 
 namespace Ui
 {
     class MainWindow;
 }
 
 using namespace MediaWiki;
 
 class MainWindow : public QMainWindow
 {
     Q_OBJECT
 
 public:
 
     explicit MainWindow(QWidget* parent = nullptr);
     ~MainWindow();
 
 private Q_SLOTS:
 
     void on_pushButton_clicked();
     void on_parcourir_clicked();
-    void on_lineEdit_textChanged(QString);
+    void on_lineEdit_textChanged(const QString&);
     void loginHandle(KJob* login);
     void uploadHandle(KJob* job);
     void processedUploadSize(KJob* job, qulonglong size);
     void TotalUploadSize(KJob* job, qulonglong size);
 
 private:
 
     void init();
 
 private:
 
     Ui::MainWindow* ui;
     Iface           MediaWiki;
 };
 
 #endif // MAINWINDOW_H