diff --git a/Tools/autotest/vehicle_test_suite.py b/Tools/autotest/vehicle_test_suite.py
index bb2c49c607064..6c47fe4143bb6 100644
--- a/Tools/autotest/vehicle_test_suite.py
+++ b/Tools/autotest/vehicle_test_suite.py
@@ -9212,8 +9212,7 @@ def upload_using_mission_protocol(self, mission_type, items):
                         m.mission_type == 0):
                     # this is just MAVProxy trying to screw us up
                     continue
-                else:
-                    raise NotAchievedException("Received unexpected mission ack %s" % str(m))
+                raise NotAchievedException(f"Received unexpected mission ack {self.dump_message_verbose(m)}")
 
             self.progress("Handling request for item %u/%u" % (m.seq, len(items)-1))
             self.progress("Item (%s)" % str(items[m.seq]))