Prohibition sign on white screen
On boot up I get the probit sign. How can I fix this?
MacBook Pro (13-inch Mid 2012), iOS 11
About the screens you see when your Mac starts up - Apple Support
Prohibitory symbol
When you see a circle with a slash symbol instead of the Apple logo, it means your Mac couldn't find a valid System Folder to start up from.
If you're using your Mac at a school or business, it might be trying to start from the wrong version of macOS. Contact your IT department for more help.
If this is your personal Mac, try reinstalling macOS using macOS recovery.
