Hyper-V Secure Boot
While I was trying to install Ubuntu as virtual machine on Hyper-V Windows, I encountered this error and unable to boot from the setup :
The image’s hash and certificate are not allowed (DB).
The problem is caused by Secure Boot option of VM. You need to open VM Settings and navigate to Security and uncheck “Enable Secure Boot”. You should now be able to boot from Ubuntu setup disk and start with the installation.