Can't install os Big Sur on Mac Book Retina 12 " early 2016
I'm trying to install Big Sur on my mac book, but I keep getting this message "This copy of the Install macOS Big Sur application is damaged, and can‘t be used to install macOS.".
This os should install on my mac book. I've tried trashing the installer and rebooting with shift held down to get into safe mode and then re-downloading the installer (as suggested in these forums) but still getting the same message.
Any help gratefully received
Mark.
MacBook, macOS 10.15