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Y2K Incidents

In brief: Y2K did not cause a disaster, but it did cause real failures. A U.S. spy-satellite ground station lost data, Japanese nuclear plants had monitoring glitches, a British hospital lab sent wrong Down's syndrome risk results to about 150 pregnant women, slot machines in Delaware stopped, and websites showed the year as "19100". This page lists only incidents backed by a cited contemporary or official source. Where sources disagree on numbers, both figures are given.

Risk level n/a (historical)
Status Historical record. For 2038-era failures that have already happened, see Known-2038-Incidents
Last reviewed 2026-10-21

Overview

The most complete official list is Appendix II, "Examples of Y2K Glitches", of the U.S. Senate Special Committee's final report (29 February 2000). It covers the U.S. and 74 other countries [1][2]. The committee warned that "the full extent of Y2K problems will probably never be known because only a small fraction of the actual occurrences will be reported", and that while its sources were considered reliable, it "was not able to verify each incident or specifically attribute it to Y2K" [1]. It also noted that 32 countries reported no incidents to the International Y2K Cooperation Center, even though reliable news services had reported incidents in those countries [1].

The incidents fall into three groups:

  1. Failures caused by the fix itself. Patches, upgrades and testing. Examples: the spy-satellite ground station, Charlotte's 911 testing outage, and Milwaukee's directory errors.
  2. Classic two-digit failures. Dates read as 1900, wrong ages or durations, and "19100" displays.
  3. Leap-day failures on 29 February 2000.

Major documented incidents

U.S. intelligence satellite ground station (31 Dec 1999 – 2 Jan 2000)

Japanese nuclear power plants (1 Jan 2000)

Sheffield Down's syndrome screening (UK, Jan–May 2000)

"19100" date displays (1 Jan 2000)

Delaware slot machines (1 Jan 2000)

Other documented incidents (selection)

Date Place Incident Ref
1999-12-29 Charlotte, NC, USA 911 systems broke down during Y2K testing [1]
2000-01 USA $50 million in Medicare payments delayed one day. One contractor received about 11,000 claims dated 1900 or 2099 [1]
2000-01 USA Seven nuclear power plants had minor glitches in non-safety systems [1]
2000-01 USA FAA Low Level Wind Shear Alert System (eight sites) and Kavouras weather display had brief problems [1]
2000-01 Knoxville, TN, USA Hundreds of utility bills printed with due dates in January 1900 or 2099 [1]
2000-01 Indiana, USA Driver licences issued with wrong expiry dates [1]
2000-01 Navajo Nation Seven of eight computer-aided dispatch servers failed. Manual dispatch until 19 Jan 2000 [1]
2000-01 Milwaukee, USA Ameritech reprinted government white pages after its Y2K software upgrade introduced errors [1]
2000-01 Lamonts Apparel, USA Filed for Chapter 11, citing slow sales and unexpected Y2K costs (about $10 million for new registers and hardware) [1]
2000-01-01 Amtrak, USA A train-tracking computer failed temporarily. Operators switched to manual [10]
2000-01 Hong Kong Police breathalyzers failed (fixed within 10 days). Futures Exchange options-pricing errors [1]
2000-01 France Ground-station communication problem related to the Syracuse II military satellite [1]
2000-01 Ukraine A nuclear plant system failure was reported to have caused a 45% reduction in power generation [1]
2000-01 Russia A boiler pump failure left 8,900 people in the Far East without heat [1]
2000-01 Jamaica Eight traffic lights (30% of the Corporate Area) went out [1]
2000-01 South Korea Graduation certificates at Korea University and court summonses dated 1900 [1]
2000-01 UK An English register office recorded 1900 on birth certificates. Racal/HSBC card terminals rejected cards [1]
2000-01 Sweden Kidney dialysis and ECG equipment problems in hospitals. Ikea store cards rejected as out of date [1]
2000-01 Denmark / Germany A newborn registered as 100 years old. Deutsche Oper payroll reverted to 1900 (press, via secondary) [11]
2000-01 New York, USA A video-store customer billed about $91,000 for a tape recorded as 100 years overdue (press, via secondary) [11]
2000-02-29 Japan Japan Meteorological Agency weather stations reported erroneous rain, wind and temperature readings. About 5% of Japan Post's 25,000 ATMs printed receipts dated 1 March [12]
2000-02-29 Boston, USA A hotel's key-card system could not issue keys until noon because the leap-year-compliant version had not been installed [12]

Risk & compliance notes

Detection & mitigation

Lessons for 2038 testing: test whole systems, not just components; watch downstream calculations (ages, durations, risk scores) as well as displayed dates; and keep checking output for months after a rollover. See Testing-and-Detection.

See also

References

  1. Y2K Aftermath – Crisis Averted: Final Committee Report, Appendix II "Examples of Y2K Glitches" — U.S. Senate Special Committee, 29 Feb 2000. The official incident list.
  2. Senate: Y2K fixes worth the billions spent — Computerworld, 6 Mar 2000. The 13-page incident list covering 74 countries.
  3. Pentagon downplays Y2K satellite glitch — Deseret News, 15 Jan 2000. Bacon's quotes and backup capacity.
  4. Pentagon Y2K satellite problem — Jim Randle, Voice of America (via FAS), 13 Jan 2000. Patch cause and duration.
  5. Electronic Weapons: January 13, 2000 — StrategyPage. Japan's six nuclear faults, the 2099 and 2036 clock jumps, and lost satellite data.
  6. Japan Y2K rollover marred by N-plant glitches — Deseret News, 3 Jan 2000. Plant-by-plant details.
  7. Y2K Bug Blamed For Miscalculated Down Syndrome Risk — Slashdot, 13 Sep 2001. Relays BBC News (BBC page not directly retrievable).
  8. Year 2000 problem — Wikipedia. 154 patients, 24 May fix, and other 19100 sites (secondary).
  9. Y2K glitch a 'black eye' for Naval Observatory — Computerworld, 1 Jan 2000.
  10. Some Y2K glitches reported around U.S. — Deseret News, 2 Jan 2000. Delaware slots, Amtrak and the Naval Observatory.
  11. 7 Problems Y2K Actually Caused — Jay Serafino, Mental Floss, 27 Dec 2019. Video-store bill, Danish newborn and Deutsche Oper (links to Time, LA Times, USA Today).
  12. Leap day skips past with few problems — James Cope, Computerworld, 1 Mar 2000.
  13. Defense: Spy system is only major Y2K failure — Bill Murray, GCN (Route Fifty), 21 Jan 2000. Outage times and when Hamre learned of it.