The retail accounting system used in all Post Office branches in the UK have experienced a major outage, with the system out of action nationally for about 90 minutes.
Subpostmasters lost business, with some reporting losing transactions that were in progress when the system crashed and their accounts were short when it rebooted.
The Post Office said the problem was with the Horizon system, supplied by Fujitsu, which is used by about 11,000 Post Office branches.
A Post Office spokesman told Computer Weekly that the outage, which he said lasted no more than an hour, was Horizon-related and added that he “believed” other retailers that use Fujitsu equipment were impacted.
Fujitsu was unavailable for comment when going to press.
One subpostmaster, who wanted to remain anonymous, told Computer Weekly that Horizon went completely offline in his branch from yesterday morning (5 November) until about 1pm.
“For us, that’s five hours of trade and we had to send so many customers away and ask them to come back later – which meant they bombarded us in the afternoon – which is no problem for us, but just a problem for the customers as they have to re-plan what they are doing for the afternoon,” he said.
“The Post Office will not tell us the exact reason for the outage – all they would say is there was a problem at the datacentre.”
Mark Baker, a subpostmaster in Wiltshire, said he experienced a couple of hours’ downtime and the Post Office had not yet explained what had happened. Baker, who is the subpostmaster branch secretary for the Communications Workers Union (CWU), said two subpostmasters had already reported to the union that they had lost transactions during the outage and were short in their accounts.
“If you have a transaction in the stack and you lose communications, the data packet that forms that transaction can get corrupted and disappears,” said Baker. “It is probably in the Post Office system and assigned to what is known as the Suspense Account.”
Baker said the problem appeared to involve a network communications failure. “If anything is to go down and take the network down, it must be something that connects systems to datacentres,” he added.
The Post Office said it will write to subpostmasters giving them details about the cause of the problem when it completes its investigation into the incident.
The Horizon system and some of the technologies and processes that support it are at the centre of a scandal that saw subpostmasters blamed for accounting shortfalls that were caused by errors in the system itself.
A Computer Weekly investigation in 2009 revealed that subpostmasters, who run Post Office branches, were being blamed for unexplained financial losses, which they claimed were caused by errors made by the Horizon system. The Post Office denied this, and many subpostmasters were subsequently prosecuted for theft and false accounting, with prison sentences, community service, criminal records and heavy fines among the injustices they suffered as a result.
This has become one of the biggest miscarriages of justice in UK history (see timeline below).