For nearly 12 minutes, the progress bar was stuck at 98.6% complete and “about 5 minutes remaining”, and on many older Macs those lasted even longer. Did the update get stuck?
Software Update
Why isn’t the progress bar for macOS updates better? Why can’t it estimate the whole time remaining to complete an update?
During a macOS update, the progress bar tells you each of the phases as they’re completed. This explains how you can track progress and make more sense of what’s happening.
How a Content Caching Server can be used to supply an update. Preflight checks are extensive, and lead on to other preparation. Finally the boot chime is muted, and the Mac rebooted to allow installation.
How Software Update settings obtains a list of available updates, and the variants that should contain. How mobile asset catalogues are checked, and preparations made to download the update.
How SilentKnight came about, and how it knows – most of the time – which version of XProtect and other security data your Mac should be using.
What to do when you know there’s an update available, but Software Update pretends that it can’t find it. With details of undocumented options for softwareupdate command and more.
Software update was completely redesigned for Big Sur, using finite state machines to enable reliable, flexible and robust updates to be applied to macOS. These are documented in log entries made during an update.
How macOS 26.2 updated to 26.3, variation in download sizes, how macOS works out free space requirements to proceed with the update, and its sequence of stages run by a finite state machine.
When the architecture of macOS switched to the Signed System Volume in Big Sur, it brought major changes in how macOS is updated, as detailed here.
The Eclectic Light Company 