“Every time user pressed Enter at a frozen interface screen”
I have never before heard of this story of an absolutely botched deployment of a new accounting system at the British post office, and “the widest miscarriage of justice in UK history.” More on Wikipedia:
Between 2000 and 2015, 736 subpostmasters were prosecuted by the UK Post Office, with many falsely convicted and sent to prison. The subpostmasters were blamed for financial shortfalls which actually were caused by software defects in the Post Office's Horizon accounting software.
Some of these bugs sound absolutely horrendous, and remind me of Therac-25:
The Horizon IT system contained "hundreds" of bugs. Some of those that came to light were named after the post offices where the bug first occurred. These bugs included: the "Dalmellington bug", where the system would enter repeated withdrawals in the ledger every time the user pressed Enter at a frozen interface screen; and the "Callendar Square bug", where the system would create duplicate database entries in the ledger.
This bit feels absolutely crucial and it seemed to me we have learned this lesson decades ago:
And while the technology had changed, the contract between the Post Office and subpostmasters, who owned their own businesses but were agents for the Post Office, remained the same. It stated that any accounting shortfalls were the responsibility of the subpostmasters unless they could prove otherwise. But without the chain of evidence created by paper-based accounting methods, proving the losses were not their fault was near impossible for many.
