Service Incident - 3rd of October 2025 - Case sensitivity ignored in dropdown fill-in question

All times in the document are recorded in UTC+2 (CEST). 

Summary
A user reported an issue where the dropdown menu in a fill-in question did not distinguish between uppercase and lowercase answers, which caused incorrect responses to be marked correct if the only difference was capitalisation. 

The issue had existed on the platform prior to discovery. After a user report, the Technical team confirmed that the behaviour did not align with intended functionality and implemented a fix to enforce case sensitivity across all existing and future dropdown lists.

An impact analysis between September 30th and October 2nd, 2025 identified 27 affected assignments, with 1388 impacted submissions. Some schools were unaffected because they had manually enabled the “Case sensitive” setting. The issue was reported on September 26th, reproduced on September 29th, and confirmed the same day. A fix was deployed shortly after, with maintenance applied to existing dropdowns. The delay in processing occurred because the initial support ticket was not treated as high priority over the weekend.

The root cause was an incorrect assumption that the “Case sensitive” setting did not apply to dropdown lists. Since dropdowns rarely contain options differing only by capitalisation, the problem went unnoticed until reported. Testing has now been improved to account for this edge case, and a script was developed to accelerate future impact analysis. Strong internal communication and structured handling ensured a timely resolution once the issue was escalated.

Lead-up
The issue that case sensitivity was ignored in dropdown fill-in questions had already been present in the platform prior to discovery. Following a report from a user, we identified that the observed behaviour did not align with the intended behaviour. A task was created, and the technical team implemented a fix to resolve the problem. 

The fix was deployed that enforced case sensitivity across all existing dropdown option lists. All newly created dropdown option lists are now case sensitive by default.

Fault
This issue had already been present in the platform prior to discovery. Below is an example to illustrate what the issue was.

Example:
Question: How do you correctly write the capital of France?

• Paris
• paris
• pariS

The correct answer is Paris. However, paris and pariS were also accepted as correct, and students received points if they selected these options.

Impact
An impact analysis was performed from September 30th 2025 to October 2nd 2025 in order to determine the affected submissions. This was scoped to 1388 submissions. Preliminary analysis suggested a higher number, but further investigation proved that some schools have manually enabled the “Case sensitive” option for their fill-in question, mitigating the issue.

The investigation resulted in 27 affected assignments, with 1388 impacted submissions.

Impacted schools have been informed.

Detection
The issue was reported by a user via a support ticket on the 26th of September at 15:10. The Support team detected the incident on the 29th of September at 9:40 after reproducing the report that was sent in by a user. A task was created immediately for the Technical team to further investigate the issue. At 12:56, the Technical team confirmed the issue.

Response
On the 29th of September at 12:56, the Technical team confirmed the issue and started working on a fix.

Recovery
A fix was implemented to address the incorrect handling of dropdown option lists. As part of this fix, a maintenance task was executed to ensure that all existing dropdown option lists are now consistently case sensitive. To avoid recurrence, we updated the platform so that any newly created dropdown option lists will, by default, always be case sensitive. This guarantees consistent behaviour across both legacy and future configurations.

Timeline
26th of September, 2025 

• 15:10 - A user reported the issue to the Support team via a support ticket.

29th of September, 2025 

• 09:42 - Support team reproduced the issue and created a task for the Technical team.
• 12:56 - Technical team confirmed the issue.

30th of September, 2025

• 11:16 - An initial impact analysis was performed to determine the number of potentially impacted submissions.
• 16:34 - Schools were informed with affected assignments that may be impacted.
• 21:24 - A fix was deployed to prevent this from happening again.

1st of October, 2025

• 16:32 - The impact analysis was refined to assess the impact on points and marks affected by the incident. Performed a preliminary calculation of what the actual values should be.

2nd of October 2025

• 16:44 - The impact was further verified and the impacted schools received further confirmation of the impact.

Reflection
This issue was caused by incorrectly assuming the “Case sensitive” setting of the fill-in question had no impact on the dropdown option lists. Combined with the fact that dropdown lists are rarely used with values that differ only in capitalisation, the issue went by unnoticed since the introduction of the fill-in question.

The first report of the incident was received on Friday afternoon, and the ticket was picked up on Monday morning. The ticket was not initially categorised as a high priority but was quickly escalated once the scope of the issue became clear.

After the functional analysis, it became apparent that dropdown lists should always be treated as case sensitive and a fix was developed and deployed. Our internal test suite was improved to account for this edge case and prevent it from occurring again.

Following a preliminary impact analysis, potentially affected schools were promptly informed and provided with a list of assignments that may have been impacted. This initial overview was provided to possibly prevent these schools from publishing results that might be incorrect.

The detailed impact analysis took longer due to the complexity of the fill-in question. In some cases, a guess correction was used which made calculating the correct score and marks more complicated. The Technical team has developed a script that allows us to perform this analysis more quickly in the future.

The steps taken in the handling of this incident were followed in procedural order. The cause was found quickly and internal communication throughout the process was strong.