Before the New Year 2000, the Swedes traded - as usual - champagne, sequin dresses and fireworks.

But in addition to the party products, another type of product was marketed. Tens of thousands of households were reached by advertising for kerosene lamps, water bags and freeze-dried wilderness food. All to cope with the consequences of a built-in computer problem - the millennium bug.

The Millennium bug or the Y2K problem, in short, was that many of the computers of the time used two characters to calculate years instead of four. When 1999 was 2000, computers understood it as a transition from 99 to 00. The fear was that 00 would be interpreted as 1900 and that the unexpected jump back in time could create unexpected data crashes.

- There were thoughts that flight computers would be confused if they suddenly thought an airplane that was in the air would land before it had launched, explains Måns Jonasson, digital strategist at the Internet Foundation.

The built-in clocks were found in almost all machines controlled by a computer. And digital systems often interact with each other. A small bug in a small system could create chain effects with unintended consequences, they reasoned.

Banks, hospitals, nuclear power plants and other community-supporting institutions were suddenly forced to carry out large inventories in their IT systems. Among private households, the question was raised about how the refrigerator, microwave oven and car would cope with the transition to the new millennium.

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During the late 1990s, enormous resources were spent on "securing" the country. In Sweden alone, an estimated SEK 40-50 billion was spent on reprogramming and replacing computers.

In April 1999, the Ministry of Industry published a brochure entitled "48 Questions and Answers on the 2000 Problem". The answers in the brochure express more calm than alarms, albeit with some reservation.

One of the questions reads: "Is the transition to the year 2000 really a big problem or just an invention of consultants?"

The answer: "The 2000 question is a real problem."

When the clock struck for the new millennium, the major disasters appeared - both in Sweden and the rest of the world.

In a report from the National Audit Office published in June 2000, a number of minor disturbances are noted. The police authority in Örebro had problems with an accounting system. At the Swedish Defense Forces radio station there were problems with an entry system. And in Värmland, the switches stopped working at three hospitals. However, no disruptions were critical to operations.

The Institute for Foreign Policy notes in a report from autumn 2001 that "most of the threats that were painted about the possible consequences of the Y2K bug were exaggerated". Among other things, it is noted that Sweden spent significantly more money on the 2000 transition compared to, for example, Russia, which is a much larger country, without the countries being significantly affected.

At the same time, the Millennium bug caused a few more serious problems. Perhaps the worst occurred in the UK where two women performed abortions after receiving erroneous results on a Down syndrome test. The incorrect responses, sent to 154 pregnant women, were described as a direct cause of the millennial bug.

What would have happened if society had not been equipped to meet the supposed IT threat, we will never know for sure. However, Måns Jonasson at the Internet Foundation believes that the proactive attitude in Sweden was good.

- The fact that almost everything went well is because the community gathered to fix these errors before they became a problem.