I am installing Ubuntu 20.04 LTS alongside Windows 10. The Windiws is installed in the EFI partitioning style. When I'm installing Ubuntu, and goes to the "Something Else" option, I am provided with a partition table where Windows is already using a ~ 100 MB EFI partition. Do I need to create a separate 512 MB EFI partition dedicated for Ubuntu?
Here's the my partition table (gparted on Xubuntu):
I assume you want to install Ubuntu in the unallocated 25 GB space at the bottom.
As you are dual booting from a single physical drive, it needs (must have) only one EFI System Partition (ESP).
This question is fully answered in If there is already an EFI partition for windows, do I need to create a new EFI partition for Ubuntu?
However: you have to make sure that you boot the installation USB in the UEFI mode when you install Ubuntu. See Installation problems with GRUB, can only install by reinstalling Windows in legacy mode but need to keep in UEFI mode for details.
The rest of the answer is devoted to subsequent questions asked in comments.
When you get to the partition selection in "Something Else" This unallocated 25 GB should show up as free space like this picture:
Highlight the free space and click on the + to create a partition. This will be the Ubuntu system partition.
/ in ext4 format:
Make sure the bootloader is installed in the first drive as a whole, /dev/sda in your case. As long as you have booted the LiveUSB in UEFI mode, the installer will find the EFI System Partition (ESP) and install part of the grub bootloader there. Never, Never, NEVER select a specific partition (like /dev/sda2) for the bootloader installation.
Continue the rest of the installation as you normally would by pressing Install Now button.
Hope this helps
You need to create a partition for Ubuntu. It cannot reside in the same partition as Windows, but apart from that no need for anything more. The 100MB EFI partition is to be mounted as /boot/efi, the partition for Ubuntu as /. Don't touch the windows partition.
EDIT: You don't seem to have much more space than the not allocated 25GB. If that is enough for you I'd allocate that as ext4 and mount it as / or shrink /dev/sda5 some and use that and the presently not allocated space for Ubuntu (ext4 mounted as/)
The way I installed Ubuntu is just by shrinking the windows partition by about 20 GB and then I just select the option to install Ubuntu along side Windows!
