Definitely true. But the software does also seem to have sucked extremely and surprisingly hard for something that was mission-critical and handling millions of pounds of transactions a day. From what I've read (which is admittedly so far less than I'd like), the whole architecture was deeply inappropriate: it wasn't just subject to a 'bug' or 'glitch'.
A key detail is that the Post Office specifically had a method for secretly and remotely editing accounts of post masters and lied about its existence. Along with experts lying under oath that the software had no known issues that could result in the account errors they were seeing, when in fact the ‘expert’ was well aware at the point that horizon was rife with such bugs.
