Provide warning to users with Qt 5.5.x about potential crash

src/gui/MainWindow.cpp

@@ -426,11 +426,15 @@ MainWindow::MainWindow()
     }
 #endif
 
-#ifndef KEEPASSXC_BUILD_TYPE_RELEASE
+#if defined(KEEPASSXC_BUILD_TYPE_RELEASE)
     m_ui->globalMessageWidget->showMessage(tr("WARNING: You are using an unstable build of KeePassXC!\n"
                                               "There is a high risk of corruption, maintain a backup of your databases.\n"
                                               "This version is not meant for production use."),
-                                           MessageWidget::Warning, -1);
+                                          MessageWidget::Warning, -1);
+#elif (QT_VERSION >= QT_VERSION_CHECK(5, 5, 0) && QT_VERSION < QT_VERSION_CHECK(5, 6, 0))
+    m_ui->globalMessageWidget->showMessage(tr("WARNING: You are using a version of Qt that causes KeePassXC to crash!\n"
+                                              "We recommend you use the AppImage version available on our downloads page."
+                                          MessageWidget::Warning, -1);
 #else
     // Show the HTTP deprecation message if enabled above
     emit m_ui->globalMessageWidget->hideAnimationFinished();