File:MacOS prohibitory symbol.png

Summary
The prohibitory symbol that is shown during the boot process of macOS when the system is not allowed to proceed.

Source

 * File:MacOS prohibitory symbol.svg by Totie / Apple Inc., Wikimedia Commons. 2016-09-30.
 * About the screens you see when your Mac starts up, Apple Support. 2015-11-01. Archived 2017-06-10.