“Volume contains a macOS or OS X installation which may be damaged”
I was recently setting up a High Sierra test partition, and this error popped up after the installer had rebooted the Mac to complete the installation. At first, I thought it was another variant of the “This copy of the Install OS X El Capitan application can’t be verified. It may have been corrupted or tampered with during downloading” error, which indicates an expired certificate. But setting the Mac’s clock back didn’t help, and neither did downloading a fresh copy of the installer.
I eventually figured out that the destination volume, though it looked empty, contained the remnants of something. After I erased it with Disk Utility, the installation proceeded normally. I think there used to be an option to “Erase and install,” which I surely would have chosen in a situation like this where I was trying to create a clean system for testing, but with no such option presented that possibility was not top of mind.
Previously:
