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Incident summary
An issue was identified where the guess score of certain questions containing choice alternatives was not updated after an alternative was removed through synchronisation. This affected multiple choice, multiple response, and order questions.
The issue could occur when synchronising either an exercise or an assignment. If an answer alternative was removed during synchronisation, the question's guess score was not recalculated. As a result, the stored guess score could become outdated and no longer reflect the current configuration of the question. For assignments with guess correction enabled, this may have resulted in incorrect participant scores and marks.
A fix for this issue was deployed on June 25, 2026, at 20:22.
An impact analysis was performed on assignments containing synchronised choice-based questions. The investigation identified 3,505 impacted results across 32 assignments.
The affected schools have been informed.
Lead-up
On June 25, 2026, at 16:04, a user contacted Support after noticing an unexpected guess score for a question containing choice alternatives.
The reported behaviour was investigated by the technical team. Initial analysis showed that synchronising either an exercise or an assignment after removing one or more answer alternatives did not trigger a recalculation of the question's guess score.
Further investigation confirmed that the stored guess score remained unchanged even though the question configuration had changed.
Fault
Choice-based questions, including multiple choice, multiple response, and order questions, calculate a guess score based on the available answer alternatives.
When an answer alternative was removed through synchronising either an exercise or an assignment, the question configuration was updated correctly. However, the stored guess score was not recalculated to reflect the updated set of answer alternatives.
As a result, the question retained the guess score that had been calculated before the synchronisation. Depending on how the question changed, this could result in an outdated and incorrect guess score being used during result calculation.
Impact
The impact of this incident could have affected student scores and marks.
An impact analysis was performed on assignments containing synchronised choice-based questions. The investigation identified 3,505 impacted results across 32 assignments.
All affected schools have been informed and provided with an overview of the impacted assignments and results.
Detection
The issue was reported by a user via a support ticket. The technical team investigated the reported behaviour and identified the underlying cause.
Response
The technical team investigated the reported behaviour and identified that synchronising either exercises or assignments did not trigger a recalculation of the guess score when answer alternatives were removed.
A fix was developed, reviewed, and deployed on June 25, 2026, at 20:22 to prevent new occurrences of the issue.
Following the deployment, questions that could be corrected without affecting participant marks were updated. In parallel, the technical team performed an impact analysis to identify assignments where the outdated guess score affected participant results. Once the complete impact had been determined, all affected schools were informed.
Recovery
A fix was deployed on June 25, 2026, at 20:22 to ensure that removing answer alternatives through synchronising either exercises or assignments correctly updates the guess score of the affected question.
Following the deployment, synchronising exercises and assignments correctly recalculates the guess score after answer alternatives have been removed. The identified affected schools have been informed and provided with the available remediation options.
Timeline
25th of June, 2026
- 16:04 - The Support team received a ticket reporting an unexpected guess score for a question containing choice alternatives.
- 16:07 - The Technical team started investigating the issue.
- 16:47 - The technical team identified that synchronising did not recalculate the guess score after answer alternatives were removed.
- 20:22 - A hotfix was deployed to the production environment to ensure that synchronisation correctly recalculates the guess score.
26th of June, 2026
- 10:37 - The Technical team shares the initial impact.
29th of June, 2026
- 11:35 - The Technical team shares the definitive impact.
- 16:09 - All affected schools were informed of the impacted assignments and results.
Reflection
This issue was caused by an omission in the synchronisation logic for choice-based questions. While synchronising an exercise or assignment correctly updated the answer alternatives of a question, it did not trigger a recalculation of the question's guess score after an answer alternative had been removed. As a result, the stored guess score could become outdated while the question configuration itself remained correct.
The issue remained undetected because it only occurred when answer alternatives were removed through synchronisation. Editing questions directly recalculated the guess score as expected, making the behaviour specific to the synchronisation workflow.
Once the issue was reported, the technical team identified the cause, developed and deployed a fix on the same day, and immediately began correcting questions where this could be done without affecting participant results. A complete impact analysis was subsequently performed to identify assignments where the outdated guess score affected participant scores or marks, after which all affected schools were informed.
This incident highlights the importance of ensuring that all mechanisms capable of modifying question content consistently trigger recalculation of derived values such as guess scores. Future changes to synchronisation behaviour will include additional validation to ensure that all dependent calculations remain consistent after question updates.
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