en.wikipedia.org/wiki/Year_2000_problem
There are two ways to view the events of 2000 from the perspective of its aftermath:
Supporting view
This view holds that the vast majority of problems had been fixed correctly, and the money was well spent. The situation was essentially one of preemptive alarm. Those who hold this view claim that the lack of problems at the date change reflects the completeness of the project, and that many computer applications would not have continued to function into the 21st century without correction or remediation.
Expected problems that were not seen by small businesses and small organisations were in fact prevented by Y2K fixes embedded in routine updates to operating system and utility software that were applied several years before 31 December 1999.
The extent to which larger industry and government fixes averted issues that would have more significant impacts had they not been fixed, were typically not disclosed or widely reported.[60]
It has also been suggested that on 11 September 2001, the New York infrastructure (including subways, phone service, and financial transactions) were able to continue operation because of the redundant networks established in the event of Y2K bug impact[61] and the contingency plans devised by companies.[62] The terrorist attacks and the following prolonged blackout to lower Manhattan had minimal effect on global banking systems.[63] Backup systems were activated at various locations around the region, many of which had been established to deal with a possible complete failure of networks in the financial district on 31 December 1999.[64]
Opposing view
The contrary view asserts that there were no, or very few, critical problems to begin with. This view also asserts that there would have been only a few minor mistakes and that a "fix on failure" approach would have been the most efficient and cost-effective way to solve these problems as they occurred.
Countries such as South Korea and Italy invested little to nothing in Y2K remediation,[65] yet had the same negligible Y2K problems as countries that spent enormous sums of money.[66]
The lack of Y2K-related problems in schools, many of which undertook little or no remediation effort. By 1 September 1999, only 28% of US schools had achieved compliance for mission critical systems, and a government report predicted that "Y2K failures could very well plague the computers used by schools to manage payrolls, student records, online curricula, and building safety systems".[67]
The lack of Y2K-related problems in an estimated 1.5 million small businesses that undertook no remediation effort. On 3 January 2000 (the first weekday of the year), the Small Business Administration received an estimated 40 calls from businesses with computer problems, similar to the average. None of the problems were critical.[68]
The absence of Y2K-related problems occurring before 1 January 2000, even though the 2000 financial year commenced in 1999 in many jurisdictions, and a wide range of forward-looking calculations involved dates in 2000 and later years. Estimates undertaken in the leadup to 2000 suggested that around 25% of all problems should have occurred before 2000.[69] Critics of large-scale remediation argued during 1999 that the absence of significant reported problems in non-compliant small firms was evidence that there had been, and would be, no serious problems needing to be fixed in any firm, and that the scale of the problem had therefore been severely overestimated.[70] However, this can be countered with the observation that large companies had significant problems requiring action, that Y2K programmers were fully aware of the variable timescale, and that they were working to a series of earlier target dates, rather than a single fixed target of 31 December 1999.[60]