one_pass | Command line client for 1Password that supports opvault | Identity Management library

The first argument of QMessageBox constructor must be a QWidget (or an instance of a subclass of QWidget), but you're passing a Ui_MainWindow object. The parent for your message box should be MainWindow.

In the setupUi() function, add self.mainwindow = MainWindow.

Then you should replace this line msgBox.information(self, 'Message', 'Data Has Been Parsed!', QMessageBox.StandardButtons) by msgBox.information(self.mainwindow, 'Message', 'Data Has Been Parsed!', QMessageBox.StandardButtons)

You can enable and disable buttons by using button.setEnabled(False) or button.setEnabled(True). As for when they are enabled, just add in the two lines above in the appropriate places to trigger the buttons.

So with your example for instance, start with simReport button disabled. Then in your select_sim_data function, add generate_Sim_Report.setEnabled(True). You can implement this functionality in any methods that need to control whether a button is enabled.