In a statement from Merlin Entertainments, who own the park, they said their investigation had concluded and that the manual override of The Smiler ride led to the tragic incident that followed.
There were found to be no technical or mechanical problems with the ride itself, and the mistake was purely an individual one, caused when the correct protocols were not followed.
Five people were seriously injured in the crash in June, with two women - Victoria Balch and Leah Washington - losing their legs after the incident.
According to a spokesperson for the park ‘a ride shutdown message was misunderstood by staff at the ride.’
‘This led to a decision to manually restart the ride, overriding the control system without appropriate safety protocols being followed correctly.’
Alton Towers have said that when the ride reopens next year, it will feature an additional level of authorisation so that a manual override cannot take place without a senior member of staff.
‘We are confident that lessons have been learned and that appropriate action has been taken to address all the issues raised by our investigation,’ said the park spokeswoman.