This is the fallback when Windows will not boot and you have no installation USB, or when bootrec keeps failing with Access is denied. With a Windows PE boot USB and the free boot utility BOOTICE, you can rewrite the MBR, the partition boot record (PBR) and the BCD store from a GUI.
BOOTICE has no single official download page and is mirrored on many sites. Scan any copy before running it, and prefer the version bundled with a WinPE build you trust. Menu labels can differ slightly between versions.
1. Check first: legacy (MBR) or UEFI (GPT)?
| Legacy BIOS + MBR | UEFI + GPT | |
|---|---|---|
| Boot code | Disk MBR + PBR of the active partition | \EFI\Microsoft\Boot on the EFI system partition (FAT32) |
| BCD location | \Boot\BCD on the active partition | \EFI\Microsoft\Boot\BCD on the EFI partition |
| BOOTICE features | Process MBR, Process PBR, BCD Edit | BCD Edit, UEFI boot entries |
In WinPE, run diskpart then list disk. A * in the GPT column means UEFI. Working in the wrong mode does nothing, so confirm this first.
2. Legacy (MBR): rewrite the MBR and PBR
- Open BOOTICE → Physical disk tab → pick the disk Windows is on (check the size so you do not pick the USB)
- Process MBR → choose Windows NT 6.x MBR → Install / Config. Windows 7 and later all use the NT 6.x code.
- Back on Physical disk, Process PBR → select the partition with the boot files (usually the 500 MB “System Reserved” or C:) → BOOTMGR boot record → Install / Config
- In Parts Manage, make sure that partition is Active; if not, select it and Activate
If GRUB or another boot loader had overwritten the MBR, this is usually enough. If you now get BOOTMGR is missing or 0xc000000f, the BCD is the problem; continue below.
3. Rebuild the BCD entry
- BCD Edit tab → Other BCD file → browse to the BCD path from the table (on UEFI, assign a drive letter to the EFI partition first)
- Open Easy mode. Delete broken entries, then Add → Windows 7/8/8.1/10 entry
- Set Disk and Partition to where Windows (C:) actually lives
- Check the boot file:
\Windows\system32\winload.exefor legacy,\Windows\system32\winload.efifor UEFI - Click Save current system, then Save globals
If the BCD file is too damaged to open, recreating it from the WinPE command prompt is faster: bcdboot C:\Windows. On UEFI, mount the EFI partition as S: and run bcdboot C:\Windows /s S: /f UEFI.
4. UEFI: restore the firmware boot entry
On UEFI, the boot entries stored in firmware (NVRAM) matter more than the MBR. Open the UEFI tab → Edit boot entries and look for Windows Boot Manager.
- If it is missing: Add → choose the disk and EFI partition → file path
\EFI\Microsoft\Boot\bootmgfw.efi→ name itWindows Boot Manager - Move it to the top with the up/down buttons and save
- If the UEFI tab is greyed out, WinPE was booted in legacy mode. Reboot the USB in UEFI mode.
5. Common sticking points
| Symptom | Cause and fix |
|---|---|
| Drops straight back to BIOS setup | Boot mode mismatch. Set UEFI/CSM back to the mode Windows was installed in |
| BOOTMGR is missing | Wrong active partition. Mark the partition with the boot files Active in Parts Manage |
| 0xc000000e / 0xc000000f | BCD points to the wrong disk/partition. Fix it in Easy mode or regenerate with bcdboot |
| Internal drive not listed | WinPE lacks NVMe/RAID drivers. Use a newer WinPE or check the SATA mode (AHCI) in BIOS |
Summary
- Legacy: Process MBR (NT 6.x) → Process PBR (BOOTMGR) → check the active partition → BCD if needed
- UEFI: rebuild the BCD (bcdboot) → add bootmgfw.efi as the first firmware boot entry
- Always confirm MBR vs GPT before you start
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