Fatal error 'grub-install /dev/sda failed' while attempting to install Ubuntu 14.04 LTS iso on opennebula 5.2 VM

trying to install ubuntu 14.04 LTS iso on VM instance but installation fails with GRUB error
please help me to solve this …

could you share your VM template so users in the forum can check what may be wrong with your VM?

Using your oneadmin user and the CLI run onetemplate show template_id where template_id is the numeric ID for your template.