Trouble installing Neon - Cannot select EFI partition

I am currently dual-booting Windows 10 and a different Linux distro, which I want to replace with Neon. My plan is to format my / partition but keep my /home partition, which is separate.

I use the latest Neon ISO, currently neon-user-20250123-1319.iso, written into a USB stick.

During installation, I select “manual partitioning” as I’ve done in the past. I select the following in it:

  • My EFI partition mounted at /boot/efi, NOT formatted
  • My root partition mounted at /, YES formatted
  • My home partition mounted at /home, NOT formatted
  • A couple of other partitions mounted at /mnt/ subdirectiories, NOT formatted.

When I click “next”, I get a popup window warning me that I have not selected an EFI partition, and I should go back and select one. However there was no special field in the manual partitioning screen to select one.

I also noticed this popup says the partition should be at least 300 MiB. My EFI partition is 99 MiB. Is this why the popup appears?

I tried to use KDE Partition Manager to enlarge it, but even after I tell it to shrink the partition after (which is the Windows one), enlarging the EFI partition is not an option.

So, two questions:

  1. Is the size of the partition the reason why that popup appears? If not, how do I “properly” select an EFI partition?
  2. If I need to resize it, how can I do it without losing data?

But has the boot flag been set in the installer? This is necessary.

If Calamares complains about the partition being less than 300mb, you can ignore it and continue, it doesn’t stop the installer from running.

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I’m quite sure it was, without me having to select it.

I think I have always had to set it myself, on any install using Calamares. The missing flag is what makes it think that there is no ESP partition, usually.

No, that’s not the issue… “Boot” is set when I open the dialogue.


It does seem like the warning is about the partition size, but like I said, the partition manager doesn’t let me change it.

I proceeded with the installation anyway, and it used the EFI partition as I told it to, so it boots fine. I guess this was only a warning.

Just a note. Neon complains efi should be 300MB, but I have 100MB EFI partition and dual booting with windows works fine too. And I can confirm I had this problem with recent iso too, when I tried to install neon onto VM. I don’t know if it was problem on a VM, but with some older neon iso I was able to select efi fine on a bare metal pc.