Apple has just released the update to macOS Sierra 10.12.6, which is available from the App Store as usual.

Its brief release notes claim that it resolves an issue making some SMB connections from the Finder, and improves the stability of Terminal. It is also believed to contain a new version of the ‘pre-release’ APFS file system, which performs normalisation to address file and folder name issues.

Apple provides a detailed list of security fixes here. They include two memory corruption bugs in Bluetooth, curl 7.54.0, Intel graphics driver bugs, and six bugs in the kernel. Sierra 10.12.6 includes Safari 10.1.2, which fixes a long list of vulnerabilities in WebKit.

Corresponding security updates (2017-003) are available for El Capitan and Yosemite.

As the update is just over 1 GB in size, and changes more than 2 GB of files on your Mac, there is clearly a lot more that is fixed which Apple is, once again, not prepared to tell us about.

The standalone Combo updater is available from here and the smaller ‘delta’ update is available from here.

Also available now are iOS 10.3.3 (which also addresses file and folder name issues with normalisation), watchOS 3.2.3, tvOS 10.2.2, and iCloud for Windows 6.2.2.

Installation

For the first time in a long period, this update did not work as advertised. Once downloaded, I clicked on the notification to restart, and nothing happened. The update (and iTunes update) were still offered in the App Store updates, as if nothing had been downloaded. But clicking to update to them did nothing either.

In the end, I quit all apps and tried a manual restart. I was then informed that there was an update waiting to be installed; I opted to install it and then restart. That seems to have knocked some sense into the App Store and its updater, and my iMac then entered a normal system update process (I hope).

The sequence on this iMac17,1 running 10.12.5 ran:

• Initial highly non-linear progress bar, white on black, starting at 16 minutes, rising to 29, then shooting forward rapidly.
• Just over half way through the progress bar, changed to a black screen, then a normal restart with a chime.
• White on black progress bar with no time estimate, then to a black screen again, and a second startup chime.
• At this stage, about 5 minutes had elapsed since the start of the update, and the white-on-black progress bar returned.
• This time, the bar started at about 80% complete, but with 16 minutes to go, and for about 5 minutes was painfully slow in making progress.
• Eventually the bar started moving more rapidly again, and my iMac returned to a normal Desktop and Finder without any login, at a total elapsed time of about 13 minutes.

Your mileage will vary.

Interestingly the iOS update, although less than 100 MB, took a very long time to install. I suspect that it was rewriting the APFS metadata in order to perform the file system update. I also wonder whether the 10.12.6 update might not have included a ‘dry run’ of the APFS converter which will be used in the High Sierra upgrade.