The first discrepancy in a result of a CHAS card holder was detected on 24 September 2018 by MOH. NCS was informed immediately, which then initially attributed the issue to intermittent network connection problems. Between 9 October 2018 and 2 November 2018, another 5 more discrepancy cases were detected and thus leading into a deeper investigation. In November 2018, NCS Pte Ltd traced the cause of the discrepancies to a software version issue used on a server used by the system. The identified issue occurred during a migration of the system to another government data center in September 2018. The software version issue was resolved as a resolution to an unrelated slow performance issue on 10 October 2018. However, incorrect results that were generated between 18 September 2018 and 10 October 2018 remained.