If you are testing beta-releases of macOS Tahoe 26.4 and use SilentKnight, you will be aware that betas 2 and 3 cause it to crash on launch, on Apple silicon Macs. This is because the firmware version returned by these betas is completely different from all others for Apple silicon Macs for the last five years. As a result of that, SilentKnight doesn’t recognise them as Apple silicon Macs, and tries to obtain their firmware versions in a way that’s only compatible with older Intel Macs.

I’m very grateful to all those beta-testers who informed me of this problem, and those who sent me crash logs.

I have now incorporated a workaround into a new build of this version. Although this doesn’t attempt to interpret the new firmware version number, which will be reported as requiring updating, this has been tested against beta 3 and does now recognise Apple silicon Macs, and shouldn’t crash. Although this should also be compatible with all other Macs and macOS that support SilentKnight version 2.12 build 59, it’s only required on 26.4 beta 2 and later. It also won’t be offered through SilentKnight’s auto-update mechanism, so if you want it, please download build 61 from here: silentknight212v61

As Apple has never documented firmware version numbers, despite revealing them in System Information, I have absolutely no idea whether this change is intentional, whether it will be used in 26.4 release, or whether it’s simply a bug. I’m hoping the last of those, because changing firmware version numbering is a sure way to create havoc, as Apple should have learned from the past.