On Sunday, in my article Home truths about macOS, I made some bold and important assertions that Apple doesn’t normally maintain even critical parts of macOS once a version has been superseded as the current release. As I wrote there: “APFS is but one example of a critical sub-system that loses all support once Apple releases a new version of macOS.”

While security vulnerabilities and their fixes draw a lot of attention, I don’t know of anyone who tries to track changes in critical sub-systems like APFS. Apple seldom makes any reference to it in its already scant release notes for macOS, and it rarely gets listed as having security bugs fixed either. All we have to go on are the version numbers that appear on different components of APFS in the /System/Library folder.

Fortunately, I’ve been tracking those ever since the first pre-release version of APFS appeared in macOS 10.12 Sierra. At first I thought that its version numbers would, like most software, reflect the pace and magnitude of change. Unfortunately they don’t, and mostly reflect the version of macOS they come in.

APFS major version numbers change with major version of macOS:

• macOS 10.12 has APFS version 0.3 or 249.x.x
• 10.13 has 748.x.x
• 10.14 has 945.x.x
• 10.15 has 1412.x.x
• 11 has 1677.x.x
• 12 has 1933.x.x until 12.2, thereafter 1934.x.x.
• 13 has 2142.x.x.

Minor version numbers increment according to the minor version of macOS, and patch numbers wander without pattern:

• macOS 10.13 went through 748.1.46 (10.13) to 748.51.0 (10.13.4 and later)
• 10.14 went from 945.200.129 (10.14) to 945.275.9 (10.14.6 with SU 2020-005)
• 10.15 went from 1412.11.7 (10.15) to 1412.141.1 (10.15.6 and .7)
• 11 went from 1677.50.1 (11.0.1) to 1677.141.2 (11.6)
• 12 went from 1933.41.2 (12.0.1) to 1934.141.2 (12.6)
• 13 has started from 2142.41.2.

Changing version numbers thus aren’t any indication of the scope or magnitude of changes made to APFS. As Apple seldom provides any information on changes made to APFS, it’s anyone’s guess as to what is going on. However, as we’d hope, the APFS engineers appear diligent in using the standard version numbering system, so it should be easy to tell whether APFS has continued to be updated once that major version of macOS has ceased being current.

Although I have only two examples to quote, I think they answer the question.

As I have written above, when macOS Catalina ceased receiving general support, with the release of 10.15.7, its APFS version was 1412.141.1. But the last security update for Catalina, released last summer, 10.15.7 Security Update 2022-005, came with APFS version 1412.141.3, two patch increments higher. Doesn’t that demonstrate how Apple has updated APFS even though it was only supposed to receive security updates?

Unfortunately not, as those two increments are fully accounted for by two security updates to APFS, released in SU 2021-002 and 2022-005, as documented in their security release notes. Other than those two security updates, the version number of APFS didn’t change in the two years that Catalina was receiving security-only maintenance.

The second is a stark comparison between Monterey and Ventura. Monterey 12.5, 12.6 and 12.6.1 all have the same APFS version number, 1934.141.2. Released at the same time as 12.6.1, the version number of APFS in Ventura is 2142.41.2. Although the numerical difference doesn’t reflect changes in code, Ventura’s APFS is a very different version, and Monterey’s hasn’t changed for three months.

Conclusions

• Evidence from version numbers of APFS, a critical sub-system in macOS, is entirely consistent with Apple’s claimed support policy, of only fully maintaining the current version of macOS, and only providing security updates to superseded macOS for two years after that.
• Do not expect to see any non-security bug fixes in any version of macOS except the current release, even in critical sub-systems like APFS.