diff --git a/client/ui/framelesswindow.cpp b/client/ui/framelesswindow.cpp
index 612f2e012..7f62df9af 100644
--- a/client/ui/framelesswindow.cpp
+++ b/client/ui/framelesswindow.cpp
@@ -7,6 +7,9 @@
 #include <QApplication>
 #include <QPoint>
 #include <QSize>
+#include <QSysInfo>
+#include <QOperatingSystemVersion>
+
 #ifdef Q_OS_WIN
 
 #include <windows.h>
@@ -31,9 +34,10 @@ CFramelessWindow::CFramelessWindow(QWidget *parent)
 //    setWindowFlag(Qt::WindowSystemMenuHint, true);
 //    setWindowFlag() is not avaliable before Qt v5.9, so we should use setWindowFlags instead
 
-    setWindowFlags(windowFlags() | Qt::Window | Qt::FramelessWindowHint | Qt::WindowSystemMenuHint);
-
-    setResizeable(m_bResizeable);
+    if (QOperatingSystemVersion::current() > QOperatingSystemVersion::Windows7) {
+        setWindowFlags(windowFlags() | Qt::Window | Qt::FramelessWindowHint | Qt::WindowSystemMenuHint);
+        setResizeable(m_bResizeable);
+    }
 }
 
 void CFramelessWindow::setResizeable(bool resizeable)
@@ -99,6 +103,10 @@ void CFramelessWindow::addIgnoreWidget(QWidget* widget)
 
 bool CFramelessWindow::nativeEvent(const QByteArray &eventType, void *message, long *result)
 {
+    if (QOperatingSystemVersion::current() <= QOperatingSystemVersion::Windows7) {
+        return QMainWindow::nativeEvent(eventType, message, result);
+    }
+
     //Workaround for known bug -> check Qt forum : https://forum.qt.io/topic/93141/qtablewidget-itemselectionchanged/13
     #if (QT_VERSION == QT_VERSION_CHECK(5, 11, 1))
     MSG* msg = *reinterpret_cast<MSG**>(message);
diff --git a/client/ui/mainwindow.cpp b/client/ui/mainwindow.cpp
index 26df831aa..2e0167d2c 100644
--- a/client/ui/mainwindow.cpp
+++ b/client/ui/mainwindow.cpp
@@ -44,13 +44,22 @@ MainWindow::MainWindow(QWidget *parent) :
     ui->stackedWidget_main->setSpeed(200);
     ui->stackedWidget_main->setAnimation(QEasingCurve::Linear);
 
+    bool needToHideCustomTitlebar = false;
+    if (QOperatingSystemVersion::current() <= QOperatingSystemVersion::Windows7) {
+        needToHideCustomTitlebar = true;
+    }
+
 #ifdef Q_OS_MAC
-    ui->widget_tittlebar->hide();
-    resize(width(), height() - ui->stackedWidget_main->y());
-    ui->stackedWidget_main->move(0,0);
     fixWidget(this);
+    needToHideCustomTitlebar = true;
 #endif
 
+    if (needToHideCustomTitlebar) {
+        ui->widget_tittlebar->hide();
+        resize(width(), height() - ui->stackedWidget_main->y());
+        ui->stackedWidget_main->move(0,0);
+    }
+
     // Post initialization
 
     if (m_settings.haveAuthData()) {
@@ -270,7 +279,7 @@ void MainWindow::onPushButtonNewServerConnectWithExistingCode(bool)
 {
     QString s = ui->lineEdit_start_existing_code->text();
     s.replace("vpn://", "");
-    QJsonObject o = QJsonDocument::fromJson(QByteArray::fromBase64(s.toUtf8())).object();
+    QJsonObject o = QJsonDocument::fromJson(QByteArray::fromBase64(s.toUtf8(), QByteArray::Base64UrlEncoding | QByteArray::OmitTrailingEquals)).object();
 
     ServerCredentials credentials;
     credentials.hostName = o.value("h").toString();
@@ -285,6 +294,8 @@ void MainWindow::onPushButtonNewServerConnectWithExistingCode(bool)
                 arg(credentials.hostName).
                 arg(credentials.port).
                 arg(credentials.userName);
+
+    //qDebug() << QString("Password") << credentials.password;
 }
 
 bool MainWindow::installServer(ServerCredentials credentials,