Since the update from Moodle 4.4.3 to 4.4.4, we get this error when duplicating a quiz or if we perform a restore by overwriting the course (this doesn’t happen when we use the option to delete the course before restoring).

Here is an example of the error we get:

Failed to find an answer matching ‘conditional answer’ in the question_answers database table. 

This occurred while restoring the question with id 6889 in the backup file, which has been matched to the existing question with id 6904 in the database. 

The problem is due to a change made in MDL-77625, in the file /backup/util/dbops/restore_dbops.class.php:

Before the modification, the question version was taken into account in this if statement:

if (isset($questioncache[$question->stamp." ".$question->version])) {

    $matchqid = $questioncache[$question->stamp." ".$question->version];

} else {

    $matchqid = false;

} 

After the fix, only the stamp is checked:

if (isset($questioncache[$question->stamp])) {

    $matchqid = $questioncache[$question->stamp];

} else {

    $matchqid = false;

} 

In our question bank, we have questions with repeated stamps. I don’t know why this happens or if it’s normal, but there seem to be more people facing this same issue with questions that have the same stamp.

I have verified that taking the version into account again in that if statement solves the problem, and we can duplicate and perform restores without any issues.
To reproduce the issue, I can’t provide steps to get questions with the same stamp, but if you manage to reach this state, to get the error you only need to:

In a course with a question bank that contains questions with the same stamp:

1.Create a quiz.

2.Add a question to the quiz.

3.Duplicate the quiz.

4.You’ll get the error I’ve mentioned.

— Replicate steps by Mark —

1. Install Moodle 3.11.
2. Create a new course "Test course 1".
3. Go the the course's question bank and create a new multiple choice question "Test question 1" with several answers.
4. Create a copy of the course, "Test course 2".
5. Go to the "Test course 2" question bank, edit "Test question 1" and change the answers.
6. From the "Test course 2" question bank, select "Test question 1" and move it to the "Default for system" question category.
7. Go to the "Test course 1" question bank, switch to the "Default for system" question category select "Test question 1", and move it to the "Default for Test course 1" category.
   • You will now have two questions called "Test question 1" in the same context, with the same stamp but different answers.
8. Upgrade to Moodle 4.1.
9. Upgrade to Moodle 4.5 (requires upgrading PHP version).
10. Go to "Test course 1"
11. Create a quiz and add one of the instances of "Test question 1" to the quiz.
12. Duplicate the quiz
    • The error is displayed.