O'Farrell is perhaps best known for her novel "Hamnet", which was made into a film directed by Chloé Zhao and nominated for eight Oscars.
She is currently working on the Swedish translation of the novel "Land", which is about a family's attempts to build a life for themselves after the Great Famine in Ireland.
The publisher Historiska Media did not give a reason for O'Farrell's departure. She was due to take part in the fair on Sunday.
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