These disruptions are happening because changing a bank's core banking application causes short-term service interruptions due to the complexity and time required for the migration. While Sterling Bank and Zenith Bank customers also experienced similar issues, GTBank's migration has caused the longest disruptions. One consultant who spoke to me claims that total integration takes months to complete and often takes longer than expected because of the "meticulous" attention to detail required to avoid errors and ensure data integrity. One product manager at a big Nigerian bank claims that banks typically integrate slowly to mitigate fraud. Banks have established security measures and fraud detection systems in place, and a sudden, complete switch to a new platform could disrupt these systems, creating potential vulnerabilities. GTBank's migration to the Finacle platform, which began in the fourth quarter of 2023, is proving to be no exception.