Mrs Maguire, 61, was celebrating her 40th year teaching at Corpus Christi Catholic College in Leeds when she was stabbed during a Spanish lesson by Will Cornick (below), who was later jailed for life for murder with a minimum of 20 years.
Her killing, in front of a class full of students, is the only time a teacher has been murdered by a pupil in a UK school.
Cornick had threatened to kill Mrs Maguire in social media postings.
Will Cornick has admitted murdering Ann Maguire
But in a report published on Tuesday, independent reviewer Nick Page, who was able to interview the teenager, concluded that: "No individual other than Will Cornick should in any way feel responsible for Ann's murder."
He said there were no warning signs known to staff or other agencies at the time, adding: "There are a number of suggested refinements to practice in Corpus Christi Catholic College but this is in no way to suggest that if implemented previously, they would have prevented Ann's murder.
"What is clear to me, as the reviewer, is that no one could have predicted or pre-empted Will Cornick's attack on Ann Maguire and following her murder, individuals and organisations acted courageously, coherently and professionally in supporting the school and affected people."
Mr Page's report said Cornick decided to murder Ann Maguire four days before he did so and told other pupils about this and about plans to kill his current head of year and another teacher and her unborn baby.
Neither staff at the school nor his parents were aware of Cornick's threats towards Mrs Maguire.
Mrs Maguire's husband Don said the review "appears to be significantly different from an early draft report which we viewed some months ago".
In a statement released by his lawyers Irwin Mitchell, he added: "Therefore our family shall need some time to read and consider its findings.
"Once we have completed this we will make a statement and I shall make myself available to answer questions or for interview."
