2038 date limit

The 2038 date limit is a forthcoming Unix-based software limitation of Mac OS X versions prior to 10.6.

As the Mac OS X operating system was based on NeXTSTEP, a Unix-based derivative developed at NeXT, early versions shared the 32-bit date range. This would cause the computer clock to cycle back to January 1, 1970 from January 19, 2038. Mac OS X 10.6 overcame this with 64-bit support. However, it was still using HFS Plus as its primary drive format, which itself had a 2040 date limit. This was addressed in September 2017 with the introduction of the Apple File System (APFS) in macOS 10.13.