A teenage boy accused of planning a “Columbine-style” attack on his former school is to face a retrial.
The 17-year-old from Loughborough in Leicestershire said the alleged attack plans, written in a notebook, were a fantasy to help him cope with bullying.
The teenager, who cannot be named, was diagnosed with Asperger syndrome after being arrested in February.
Recorder of London Judge Brian Barker QC discharged the jury of six men and six women following six days of deliberation.
A hearing will take place at the Old Bailey on 12 December to set a date for a retrial.
The teenager has already admitted three charges of possessing explosives.
The trial heard that he was fascinated with mass murders and school shootings and expressed anti-Islamic views.
Police discovered weapons including partially-assembled petrol bombs and air rifles after searching the teenager’s home in February following reports he had confronted two boys with a knife.
The prosecution alleged that he had these for a purpose connected with terrorism, but the teenager denied this.
The trial heard that he listed six potential targets in his home town of Loughborough, including a mosque, council offices and cinema.
He claimed he had not intended to hurt anyone and his notebook contained “jottings, not actual plans”.
Jurors were also told that two of his friends, also aged 17, had admitted possessing explosives.