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The Point of Failure

Episode 10 · The Tiny Bug Hall of Fame · 1:47

The Disaster That Never Happened

00:19 · Point of failure

Two-digit years made the millennium rollover a real software risk. Years of remediation and testing helped keep the disruption limited, leaving successful prevention looking like an unnecessary warning.

The Point of Failure, Episode 10: The Disaster That Never Happened

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Incident

Topics
date handling · prevention · testing · reliability
Point of failure
Years were stored as two digits to save memory, so to millions of programs the year 2000 read as 1900.

Transcript

250 words · 1 min read

The quiet rollover

The biggest software rescue in history is remembered as a joke. This is The Point of Failure, episode ten.

Quick show of hands if you've heard Y2K was overhyped. Nothing really happened, right? Planes did not fall. Banks did not collapse. Everyone laughed. Here is what actually happened.

Two digits

Point of failure

For decades, computers saved memory by storing years as two digits. 1999 was just 99, which means the year 2000 becomes 00. And to millions of programs, 00 means 1900. Loans calculated across negative time. Schedules a century off. Systems that simply refuse.

The work before midnight

So the world did something we have honestly never done at that scale since. Hundreds of thousands of programmers spent years reading ancient code, line by line, fixing dates. Companies and governments spent an estimated 300 to 500 billion, quietly, before the deadline.

Midnight came. A few scattered glitches around the world. And that is the whole story. The asteroid was real. We moved it. And because we moved it, everyone decided it was never coming.

What prevention looks like

Here is the curse of everyone who works in reliability. When you fail, it's a headline. When you succeed, it's a Tuesday. Y2K was not a punchline. It was proof that we can see disaster coming and beat it if we do the boring work early.

Every failure has a story. Every story was preventable. I'm Kevin. See you in the next one.

Sources

4 sources

  1. Year 2000 Computing Challenge: Leadership and Partnerships Result in Limited Rollover Disruptions

    U.S. General Accounting Office · 2000

  2. Year 2000 Computing Crisis: Success Depends Upon Strong Management and Structured Approach

    U.S. General Accounting Office · 1997

  3. Mr. Kelley discusses the Year 2000 issue

    Bank for International Settlements / Federal Reserve Board · 1998

    Contemporaneous estimates varied: this speech cites Gartner’s forecast of $300–600 billion worldwide, not an audited final cost. The episode uses an estimated $300–500 billion range.

  4. What Happened to Y2K? Koskinen Speaks Out

    The Co-Intelligence Institute · 2000

    Interview with the chair of the President’s Council on Year 2000 Conversion discussing prevention and the uncertainty in global spending estimates.

  1. 12

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    On 6 December 2018, an expired certificate in Ericsson core-network software disrupted operators across 11 countries. O2 and SoftBank were among the networks affected by the same dated dependency.

  2. 18

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    In June 2012 an upgrade to the batch scheduler at RBS was backed out along a path nobody had tested, and the two versions turned out to be incompatible. Jobs stopped reaching the overnight queues, the backlog compounded night after night, and at least 6.5 million customers of RBS, NatWest and Ulster Bank lost reliable access to their money, some of them for weeks.

  3. 08

    Sell 1 Share... or 610,000

    On 8 December 2005 a Mizuho Securities order to sell one J-Com share at 610,000 yen went out inverted, as 610,000 shares at 1 yen. The desk tried to cancel within seconds, and a defect in the Tokyo Stock Exchange's own system would not let the cancellation through.