Please help: Strange problem installing Ubuntu

[jeffjot]

While installing Ubuntu, most recent version (20) I can never get past the 4th screen.
Its on a brand new computer which has Windows 10, and I've already shrunk the filesystem to create a dual boot, and there is a huge (700 gig) unallocated space on the disc.

I boot Ubuntu off a bootable USB iso, click the install Ubuntu icon.... go past Language, Keyboard, and Install Multimedia Codecs. And thats where things tank.

Instead of the next screen expected, it goes directly to a page which shows "Installation Type" with a bunch of headers: Device, Type, Mount Point, Format?, Size, Used, System.

There is a blank white empty space underneath that.

At the bottom is: "Device for boot loader installation:" and there is only /dev/sda, nothing else selectable on the drop-down. I'm assuming, /dev/sda is the USB flash drive where the bootable Linux is.

Now, everyone says "SET THAT TO /!" but there is no possiblity or way to do that.
Nothing can be typed.
The only option is to click "Change", and that causes the installation to crash.
What could be causing this? No instructional walk-thru mentions anything of the sort.

I also can't see any way to view the unallocated space on the hard drive. I appear to only be seeing the USB stick, nothing more.
?????

[SeijiSensei]

No, /dev/sda is the primary hard disk in the computer. It's where you want the boot loader to be installed.

[GhX6GZMB]

As SeijiSensei says, sda is your primary disk, but this still has to partitioned.
/ and boot are not the same, boot is a small separate partition with a size of around 1 GB (may vary) that contains the boot loader.

Where you place / and /home etc. is a different issue.

[jeffjot]

I have no choice to go any further is what I am saying.
If I click "Install Now" with the preselected /dev/sda, I get a message:

No Root Filesystem
No root filesystem is defined.
Please correct this from the partitioning menu

My only option is to click "OK".
When I click OK, I'm still at the same screen, stuck.

The drop-down allows no other selection.
"Change" and "+" cause the installation to crash.
"-" does nothing.

There is no way forward.

[QIII]

@jeffjot -- given that a picture is worth a thousand words, could you take a shot with your cell phone and post it here?

[jeffjot]

It looks exactly like this:

[1fallen]

Looks to me to be a UEFI issue.

[jeffjot]

Uefi?

[jeffjot]

What is it supposed to look like?
Every option goes nowhere. Except Quit, which of course quits.

[1fallen]

Your supposed to see a drive in blank area you show on your photo.
If your still using the live-installer, open a terminal and run:

sudo dmesg | grep "EFI v"

If it shows anything your in UEFI mode.
EDIT: I just read your first post "New machine with Win 10" your definitely in UEFI.