When trying to install CentOS 8 in my Desktop with a asus motherboard that supports UEFI and secure boot I got the error
/images/pxeboot/vmlinuz invalid signature, googling I found that it was about secure boot and that I had to disable secure boot, I did that. But still got the error.
Then I kept looking and read that you can prevent grub to check the signatures if disabling a environment variable like this:
set check_signatures=no and still got the error.