Illustration: Sarah Grillo/Axios

When the popular free-stock-trading app Robinhood went offline Monday and Tuesday, Twitter wags immediately opined that programmers must have failed to account for this year's quadrennial Leap Day, which fell on Saturday. The firm eventually denied that scenario, pinning the crash on simple infrastructure overload.

The big picture: But it wasn't a bad guess. Calendar quirks have always been a predictable source of software bugs. We think of the measurement of time as a science, but it is also a human art, encrusted with customs, exceptions and historical quirks.

  • Time zones are irregular.
  • Times are a.m. and p.m. except when they're on a 24-hour clock.
  • Different countries format dates differently.
  • To remember how many days each month has, people need mnemonic rhymes!
  • Computers are great at keeping track of all these things, but the people who program them still make goofs trying to account for all of the cases.

Y2K: Two decades ago, a bug associated with the flip of the millennium counter threatened a Y2K doomsday that never materialized, whether because the danger had been overhyped or because freaked-out companies hauled enough COBOL programmers out of retirement to fix everything.

2038: Today, Unix programmers are already preparing for the "Year 2038 bug." Some versions of Unix will break in that year as the number of seconds that have passed since Unix time began in 1970 grows too big to hold in a 32-bit register.

Daylight savings time: The clock's seasonal adjustments used to cause many systems to throw fits. Modern systems handle them smoothly, for the most part — but every time the clocks move forward or back, the brains of your local sysadmins, IT crews, and tech-support teams ache from their old war wounds.

What's next: The U.S. moves its clocks forward this coming weekend. Everybody ready?

Go deeper

TikTok's content-moderation time bomb

Illustration: Aïda Amer/Axios

When the dust finally clears from the fight over TikTok, whoever winds up running the burgeoning short-video-sharing service is likely to face a world of trouble trying to manage speech on it.

Why it matters: Facebook’s story already shows us how much can go wrong when online platforms beloved by passionate young users turn into public squares.

Ben Geman, author of Generate
36 mins ago - Energy & Environment

Zooming in on China's new energy plan

Illustration: Rebecca Zisser/Axios

Major climate news arrived on Tuesday when Chinese President Xi Jinping said China would aim for "carbon neutrality" by 2060 and a CO2 emissions peak before 2030.

Why it matters: China is by far the world's largest greenhouse gas emitter. So its success or failure at reining in planet-warming gases affects everyone's future.

Updated 56 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 9 a.m. ET: 31,647,930 — Total deaths: 971,711 Total recoveries: 21,776,599Map.
  2. U.S.: Total confirmed cases as of 9 a.m. ET: 6,897,661 — Total deaths: 200,818 — Total recoveries: 2,646,959 — Total tests: 96,612,436Map.
  3. Health: Hospitals want more time to repay pandemic loans — Supply shortages continue to plague testing.
  4. Business: The high-wage jobs aren't coming back
  5. Vaccines: Johnson & Johnson begins large phase 3 trial — The FDA plans to toughen standards.
  6. Sports: Less travel is causing the NBA to see better basketball.

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