https://bugs.launchpad.net/ubuntu/+source/hplip/+bug/1718129

Index: ui/scrollunload.py
--- ui/scrollunload.py.orig
+++ ui/scrollunload.py
@@ -120,7 +120,7 @@ class ScrollUnloadView(ScrollView):
                 self.pc = photocard.PhotoCard(None, self.cur_device.device_uri, self.cur_printer)
             except Error as e:
                 QApplication.restoreOverrideCursor()
-                self.form.FailureUI(self.__tr("An error occured: %s" % e[0]))
+                self.form.FailureUI(self.__tr("An error occured: %s" % e.msg))
                 self.cleanup(EVENT_PCARD_UNABLE_TO_MOUNT)
                 return False