file name: ubuntu-18.04.1-desktop-amd64.iso. currently windows 8.1 installed on my laptop. I am trying to install ubuntu from usb flash drive and created a bootable usb using rufus. When I boot from usb it gave me four options. try ubuntu, install ubuntu, oem install and check disk
when I select the option 1 (try ubuntu) or option 2 (install ubuntu) then it gives me an error message saying
18.206119 Problem Loading UEFI:db X.509 certificate (-65)