UEFI Install Missing Boot Partition | Generated by AI

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Question: Install failed and rebooted back to the partition screen — Disk 0 now shows MSR + 476.9GB Primary (no EFI System Partition), and there’s a separate Disk 1 with a leftover 200MB System + 14.5GB “WIN11” partition — what’s wrong?

Answer: Two things stand out here that explain the failure:

1. Disk 0 is missing its EFI System Partition. A proper UEFI/GPT Windows layout needs 4 partitions: EFI System Partition (FAT32, ~100–260MB), MSR (16MB), Primary (Windows), and Recovery. Your Disk 0 only has MSR + Primary — no ESP. That pattern (MSR + Primary, no ESP) is what Setup creates when it thinks it’s doing a Legacy/MBR-style install, but you already ran convert gpt in diskpart. So now you have a GPT disk with an MBR-style partition layout — the firmware can’t find a bootloader after the first reboot, which is exactly why it fails after restart.

→ Fix: check BIOS boot mode. Reboot into BIOS (F2 or Novo button on Xiaoxin), find Boot Mode / UEFI/Legacy Boot, and make sure it’s set to UEFI only (disable CSM/Legacy/Compatibility Support Module). If it’s currently on Legacy or “Both”, that’s the root cause.

2. Disk 1 is a second, tiny (14.7GB) drive with a half-finished Windows install on it. That “200MB System + 14.5GB Primary: WIN11” is leftover from install attempt(s) landing on the wrong disk — 14.5GB is too small for Windows 11 (needs 20GB+ minimum, realistically 64GB+). This is likely your Xiaoxin’s eMMC/cache storage, not the main SSD. Ignore/don’t touch it as install target — your real target is Disk 0 (the 476GB one).

Steps to redo cleanly:

  1. Enter BIOS → set UEFI boot mode, disable CSM/Legacy → save & reboot back into Setup.
  2. On Disk 0: select Partition 1 (MSR) → Delete. Select Partition 2 (476.9GB Primary) → Delete. Now Disk 0 = fully unallocated.
  3. Select the unallocated space on Disk 0 → Next (let Setup auto-create all 4 partitions this time — you should now see EFI System Partition appear).
  4. Do NOT select Disk 1 at all.

If BIOS was already set to UEFI-only and this still happens, tell me and we’ll check if Secure Boot or a fast-boot setting is interfering instead.

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