No bootable device after successful installation

Question

I downloaded the latest release of Sophos XG Home (SW-18.0.1_MR-1-Build396-396.iso) and installed it to my machine. Specs, for reference: AMD Ryzen 3 3200G Gigabyte B450M DS3H 2x 8GB Corsair Vengeance LPX DDR4 (yea, I know it only uses 6GB :/ ) 2TB Seagate Barracuda Compute HDD Ubit RJ45 x 4 Gigabit LAN PCIe adapter Ubit RJ45 x 2 Gigabit LAN PCIe adapter 
 I successfully made a bootable USB drive with the installer image using Rufus in DD mode and completed the install process. Upon completion, it asks me to remove the USB installer and reboot. I remove it, reboot, and the system cannot find a bootable device. I've installed a half dozen times at this point, tried multiple HDDs and played with all the BIOS settings I can think of that could be relevant with no change. 
 I have seen a couple other similar topics on here that were unhelpful. One suggested trying Easy2Boot to manually boot the drive, but that was ineffective for me, it would just hang after selecting boot from first hard disk. 
 If anyone has any insight or suggestions, they would be most welcome. Thanks!

Prism · Accepted Answer

RyzenShine said: Are there any BIOS settings it might be sensitive to that I could be overlooking? 
 I'm currently using a Ryzen 3300x in a B450M, on the first time I've installed It also didn't boot correctly. 
 
 Be aware, Sophos XG can't boot thourgh UEFI, you will need to enable full support for legacy BIOS. 
 You can do this by enabling CSM on the BIOS. 
 Also check your boot order, on my XG MR2 installation, even that It didn't support to boot through UEFI, GRUB still created an UEFI boot option. So you will need to change the boot order to your hard drive in the BIOS. 
 
 And, there's no problem overclocking. 
 
 RyzenShine said: I successfully installed it on an old i7-930 rig with dual Realtek NICs with no issues. 
 Also, if you still have errors on this, you can use the (fully workable XG) hard drive from your old i7-930 on the new 3200G. Just throw it on your computer and fix the boot order. 
 I've this when I had errors migrating from a G5400 to a Ryzen 2200G. 
 
 Thanks!

RyzenShine · Answer

So, the install from my i7 actually worked, so I installed it to the new drive using my i7 system and shut it down and transferred it over after the initial install was complete and before initializing anything and it seems to work. Really weird considering it says it installs successfully on the new system but then won't boot. I have all the CSM options set to legacy in the BIOS and that made no difference, but it seems like if you can install it elsewhere first you can transfer the install over. Very helpful -- thanks.

Neo Zen · Answer

The problem you are having is that even though the Sophos XG install program is UEFI bootable, Sophos XG itself is not. 
 That's why you are are to install Sophos XG from a UEFI bootable USB stick, but later when the install successfully completes, your computer can't start Sophos XG from the HHD 
 The solution? You have to manually make the Sophos XG in your HHD UEFI bootable.. 
 How? Follow these simple steps.. 
 1. Create a USB install of Ubuntu Live 18.04 (Must use only Ubuntu 18.04, since newer versions have a different (newer) GRUB version and won't work) 
 2. Boot Ubuntu 18.04 from your USB stick (DO NOT INSTALL, just select TRY Ubuntu) 
 3. Once in Ubuntu, open a terminal/command prompt window and enter the following: 
 sudo apt install grub-efi-amd64-bin sudo mount /dev/sda1 /boot sudo mkdir /boot/efi sudo mount /dev/sda2 /boot/efi sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi/ 
 4. Once done, take out the Ubuntu USB stick and reboot. 
 What this does is that it installs GRUB to your Sophos XG install and makes it UEFI bootable.. 
 You can now disable CSM, since it's now UEFI bootable. 
 So.. How do I know all this? I've been through this too, when I upgraded my Sophos XG Firewall to v18 MR-1 
 You can find more info here: 
 https://community.sophos.com/products/xg-firewall/f/initial-setup/120175/uefi-boot-xg-firewall-18-0-ga-build379#pi2151=2 
 
 Thank Martin Gross for this solution... I'm just passing it along :)