Comment 55 for bug 1767703

Is this really a bug?
In my opinion it is not.
This is just a user fault.

The solution of this problem relies on two basic steps. At first you need to create your Ubuntu 18.04 bootable flash drive correctly. And secondly, you need to bootup you machine using the bootable flash drive in the correct mode (UEFI/CSM/Legacy BIOS). When your system is MBR Partitioned with legacy BIOS and you try to install Ubuntu in UEFI mode, failure of the installation process is natural.

You may want to read more:

https://abcsofubuntu.blogspot.com/2018/05/how-to-fix-grub-installation-failed.html