What Day Was the Y2K new year rollover?

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The world's clocks rolled over from 1999 to 2000, an event preceded by years of concern over the "Y2K bug" — the risk that computer systems representing years with only two digits would misinterpret "00" as 1900 rather than 2000, potentially causing widespread software failures.

Extensive remediation work in the preceding years, combined with the fact that many systems were more robust than feared, meant the actual rollover produced only isolated, minor issues rather than the severe disruptions some had predicted.

Total remediation spending to fix Y2K-vulnerable computer systems worldwide has been estimated by various analysts in the hundreds of billions of dollars, one of the largest coordinated global technology fixes ever undertaken.

Some of the most extensive Y2K remediation work took place in sectors like banking, aviation, and utilities, where even minor date-calculation errors could have cascading operational consequences.