kivy: initialize app.android_backups from config, and show error message if save_backup raises an exception

electrum/gui/kivy/main_window.py

@@ -381,6 +381,7 @@ class ElectrumWindow(App, Logger):
         self.daemon = self.gui_object.daemon
         self.fx = self.daemon.fx
         self.use_rbf = config.get('use_rbf', True)
+        self.android_backups = config.get('android_backups', False)
         self.use_unconfirmed = not config.get('confirmed_only', False)
 
         # create triggers so as to minimize updating a max of 2 times a sec
@@ -1244,7 +1245,12 @@ class ElectrumWindow(App, Logger):
         request_permissions([Permission.WRITE_EXTERNAL_STORAGE], cb)
 
     def _save_backup(self):
-        new_path = self.wallet.save_backup()
+        try:
+            new_path = self.wallet.save_backup()
+        except Exception as e:
+            self.logger.exception("Failed to save wallet backup")
+            self.show_error("Failed to save wallet backup" + '\n' + str(e))
+            return
         if new_path:
             self.show_info(_("Backup saved:") + f"\n{new_path}")
         else:

electrum/gui/kivy/uix/ui_screens/status.kv

@@ -81,7 +81,8 @@ Popup:
             Button:
                 size_hint: 0.5, None
                 height: '48dp'
-                text: _('Save Backup')
+                text: _('Export Backup')
+                disabled: not app.android_backups
                 on_release:
                     root.dismiss()
                     app.save_backup()