Y2K bug is the biggest mistake of computer engineers in the 90s actually when the computer architecture designed then computer engineers not think about the date format on that time they use format DD-MM-YY and in the 90s they realized when the 2000 year coming after that the complete dates in arrow system start from the 00.
And due to this issue on computer defined system will be stuck in the 2000 year example academic economic and legal related area will be stuck because everything is based on the date year and according to the Y2k issue year will be set as zero after 2000 year then it is started from the 01 and by this all debt related system will be wrong
To fix this issue United State spoil $300 billion to fix this issue and this issue solved by the Indians for more you can watch this video.