A lazy fix to the Y2K bug caused software issues when the date rolled over to 2020. Later this year, programmers also avoided a Y2038 bug, pushing the problem back to 2486
Source:
https://www.newscientist.com/article/mg24833130-300-2020-in-review-revenge-of-the-y2k-bug-as-lazy-fix-takes-down-software/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home