The series of blunders in this year's A-levels and GCSEs were "unusual" and do not show an overall failure of the exams system, it has been suggested.
Around 100,000 students in total were thought to have been affected by mistakes found in about 12 different exam papers this summer.
The errors ranged from wrong answers in a multiple choice paper, to impossible questions, and printing mistakes.
The exam boards involved have published the findings of their own inquiries into the blunders.
The Joint Council for Qualifications (JCQ), which represents the awarding bodies, said there had been an "unusual cluster" of unrelated errors this summer.
In a statement, JCQ director Dr Jim Sinclair said: "Today's publication of the findings of the investigations shows there was no systemic failure of the exam system.
"The number of major errors reported in 2011 represents an unusual cluster of unrelated errors appearing in one year. As the awarding bodies have detailed, there is a separate explanation for each individual error.
"The findings highlight that although there are areas in which awarding bodies can make improvements to their own processes to minimise the risk of mistakes, the system itself operates to a very high standard with an extremely high level of accuracy."
He added: "Awarding bodies are now acting on their findings. The steps they are taking over the weeks and months ahead will make their processes even better and help restore confidence in the examination system."
Shortly before A-level and GCSE results were published last month, the five exam boards responsible for the errors promised affected teenagers that they will "get the grades they deserve". In a joint statement, they said they wanted to "reassure" students that they would not be disadvantaged.
