Wasn't the y2k issue programs that stored numbers as binary coded decimal and only allocated one octet (i.e. two digits) to the date?

BCD could be one of many problems, but ASCII strings would me more common in systems I dealt with. There were a lot of assumptions about two digit years that maybe made sense sometime in the 70s for code that you didn’t think would survive more than a few years.

Also take a look at struct tm. Its tm_year looked like just a 2 digit year and as such people may format it with printf(“19%02d”,…). It is actually the number of years since 1900. In early 2000 I had to fix a broken ftp server that was sending 19100 as the year.

The only manifestation of Y2K that I ever saw was a receipt with the date 1/2/100.

I saw that in websites with Perl-generated dates.

Y2038 is also a data format issue (32-bit dates).

I think it's likely to be better handled, but at the same time people keep citing the non-disaster of Y2K as a reason not to do disaster preparation, so I don't know.

True, but it's not like a birth date - this one goes very deep into the core of the operating system.