Boot up: no entry followed by Apple logo and boots fine.
I have my Apple Imac running the latest install/build of Catalina 10.15.6, however noticed when it boots it gives me a No-Entry sign then reverts to a boot up progress bar and loads fine.
There are no errors on the First Aid on any of my drives / data or USB drives, but I can see from an older post from May, that having another OS/X on a drive as bootable could cause this.
Since I have Mojave bootable permanently attached and also a short cut to allow me to boot to Catalina/Mojave from under System. I was wondering if my boot up process was trying the USB (Mojave) to boot from (even though Catalina is the Startup Disk) before reverting back to the Catalina and booting fine.
Weirdly if I set Mojave to boot as StartUp, I dont get any No-Entry sign, its only when Catalina boots, and all repairs/disk checks and diags have not reported any errors on any hardware, plus it doesn't stop on boot up and once the no-entry goes (After 1-3 seconds), it then boots up with the progress bar fine and gets me to the icons to login.
Is this a bug in OS/X where it boots and as there are two drives with the OS/X its causing the No-Entry?
Chris
iMac, macOS 10.12