"The Casual Vacancy," released in the United States by publisher Hachette, had a formatting problem that caused it to be displayed on some e-readers in either a large size that showed a limited number of words per page or in tiny-sized type, the BBC reported Friday.
Hachette acknowledged it was responsible for the fault, which kept font and margin sizes from being adjusted, and said it has released a fixed version.
"As soon as Hachette was made aware of these issues, a replacement file was uploaded to all e-book retailers," the company said in a statement.
The book topped several e-book charts ahead of its release due to high interest following Rowling's success with her "Harry Potter" series.
The U.K. publisher of the book, Little Brown, said users in Britain were been affected.
Strict embargoes imposed on the book's release might have prevented Hachette staff from noticing the formatting problem before the e-book went on sale, PaidContent, the website that first reported the issue, said.