For the “damaged” error, also verify the installer integrity via shasum -a 256 /Applications/Install\ macOS\ Catalina.app . A valid hash should match publicly available checksums (check Apple forums for latest).
“macOS Catalina 10.15.7 Installer Updater has finished. Rebuilding bootable snapshot. Estimated time: 47 years.” macos catalina 10157 installer upd
Leo’s stomach turned cold. July 17, 2022 — that was the day his external drive had failed mid-restore. He had abandoned it, wiped the drive, never looked back. How did this installer know? For the “damaged” error, also verify the installer
macOS Catalina 10.15.7 Installer & Update Report macOS Catalina 10.15.7 is the final major version of the Catalina operating system. While it has officially reached its general end-of-life, it recently received unexpected security updates in early 2026 to maintain critical services like iMessage and FaceTime. Rebuilding bootable snapshot
