1. Create a quiz with one essay question.
2. Make two attempts as a student, putting an answer into the essay question.
3. As teacher, go to the quiz grades report, and verify that both attempts require grading.
4. Manually grade the second attempt.
5. Go to the quiz statistics report. Verify that there is no fatal error, and that it says
Number of complete graded first attempts 0
Total number of complete graded attempts 1