Here's another timezone bug. With a correct timezone file, I once tried to convert a local time of 2018-03-23 02:15 to UTC time. It failed with some sort of "incorrect date/time value" exception. It was buried in a big batch of otherwise correct data, which made it worse to track down. It turned out that, in my timezone (America/New_York) that time didn't exist! That was daylight time switchover day in 2018. The local clock ticks from 01:59 to 03:00 on that day.