There’s more to the quarantine flag, as it’s not binary on/off, and app translocation can trap even notarized applications if you don’t move them right.
quarantine
You unarchive a freshly downloaded app and try to give it a test run. It immediately crashes. Here’s one common reason, and how to solve it very simply.
Quarantine flags first appeared in 2007. This explains how they work, what they do, and the differences between app and document quarantine.
From the start of voluntary code signing in 2007, defences against malware in macOS have changed dramatically. Here’s an overview of what has happened.
Why does it take 2 years to realise that macOS has been checking signing certificate validity online?
If you were to strip unwanted code from a Universal App, would it still pass Big Sur’s strict security checks?
AirDrop is very convenient, but sets the quarantine flag, which can break Apple’s installer apps. Here’s how to remove those flags in a couple of minutes.
How Catalina and Big Sur handle the first run of apps which have their quarantine flag set. With details of log entries seen in both steps needed for approval.
All about xattrs: their origin, where they’re stored, how they’re named and typed, how to find and work with them, and their common problems.
Utility to strip spurious quarantine flags from documents in folders, now runs native on Apple Silicon.
The Eclectic Light Company 