Later in the ride's life, a major crash caused by human error occurred on June 2, 2015. The ride was closed for 9 months until it reopened in March of 2016. The ride has been operating incident-free ever since..

Since the high-profile accident in 2015, The Smiler at Alton Towers has undergone rigorous safety enhancements and is considered safe for operation in 2026. Following the incident, the park implemented multi-layered technical fail-safes, including new computer-controlled block systems that make it physically impossible for two trains to be on the same section of track simultaneously. The ride is subject to daily mechanical inspections and frequent independent audits by the Health and Safety Executive (HSE). While the coaster is famous for its world-record 14 inversions and high-G forces, it operates under the same strict European safety standards as any other world-class theme park attraction. In 2026, the ride's "sensors" are notoriously sensitive; any minor obstruction (even heavy rain or a dropped phone) will cause the ride to "stop-and-reset" automatically, which is a sign of the system's high-functioning safety protocols rather than a mechanical failure.