The Alton Towers rollercoaster crash in June which seriously injured five people was caused by human error, according to the theme park.
Staff misunderstood a shutdown message and wrongly restarted the ride, an investigation by the park confirmed.
No technical or mechanical issues were found with the ride itself.
The Smiler ride, which has been closed since the crash, will re-open at the Staffordshire park next year with improved safety measures.
"A ride shutdown message was misunderstood by staff at the ride," an Alton Towers spokeswoman told the BBC.
"This led to a decision to manually restart the ride, overriding the control system without appropriate safety protocols being followed correctly."
A total of 16 people were injured when the carriage they were in collided with an empty one that had come to a halt ahead of them. Four people sitting in the front row were among those most seriously hurt including two women who had legs amputated.
The Health and Safety Executive said its own investigation was "still ongoing".
Alton Towers said it had followed "standard HR procedures and taken the appropriate action" when dealing with the staff whose errors caused the crash.
A spokeswoman said: "The outcome of this however remains a private matter between us and any individual concerned."
When the ride re-opens next year, it will feature an additional level of authorisation so no manual override can happen without a senior member of staff, the theme park said.
"We are confident that lessons have been learned and that appropriate action has been taken to address all the issues raised by our investigation."
Park owner Merlin Entertainments previously disclosed that significantly lower numbers of visitors to Alton Towers over the summer had prompted a restructuring of the business which could see 190 job losses following an 11.4% fall in revenues.
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