A spokeswoman blamed a 'technical issue' with one of the supports on The Smiler, which launched in?May.
It has now reopened. The spokeswoman said: "It wasn't a safety issue. It was picked up during standard daily checks. The cracks were at the surface where the bolts go in."
The park's website said that the ride, which has 14 loops, is expected to reopen 'soon'.
Disappointed thrill-seekers who had travelled from across the country to visit the theme park took to social media websites to express their dismay at the closure.
Wendy Hewitt wrote on Facebook: "We've just come back from a three day stay at Alton Towers especially to go on the Smiler.
"It was shut all three days and several other rides broke down making it the worst break we've ever had there.
"Could you let me know who I should complain to please as I'm really annoyed about this."
The 53mph ride first shut last month after a 12-inch metal bolt reportedly fell from the 3,839ft track near a queue.
It also broke down on its preview night in May, leaving riders dangling for 30 minutes. No one was hurt.
Sixteen invited guests sat for over an hour in their carriages after the rollercoaster halted just seconds after setting off.
Construction on The Smiler, which lasts two minutes 45 seconds and features a 98ft drop, began early last year.
The theme park company said the ride 'pushed the boundaries' when it opened to the public on May 23.