Whether it’s a full macOS update, or a small Security Update, it can go wrong. Here’s a systematic guide to the solutions you can try to restore normal function.
Looking at what’s involved in updating Big Sur’s new Sealed System Volume shows what’s necessary for successful cloning.
in a Ghost Train or Dark Ride, one minute everything’s gone black, then all hell breaks loose. Just like a T2 Mac installing a macOS update.
Follow Apple’s instructions for a clean re-install, and you’ll probably hit an error, and be left floundering in Recovery mode with an unbootable system.
Safe mode, installing the Combo updater, re-installing macOS, and other potential solutions to get that update working properly.
How to check whether a macOS Installer app still has a valid signature, and where to find its hidden Installer packages.
Links to official Apple support articles, and important 3rd party pages. How to run Aperture in 10.15, where to get old versions of macOS, and much more.
No more fiddling with contextual menus: this new version also adds a busy spinner, and opens older packages too.
How to check whether any Installer package or app has valid certificates, using this new version of Taccy.
Validating signatures isn’t straightforward. GUI apps are limited, and command tools confusing and prone to user error.