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Restore the Recovery Environment and Repair the Boot Record

When the recovery tools vanish or the machine stops booting: reagentc, bcdboot and the order of commands that actually fixes it.

by@guidox updated:10/31/26 time:45 min level:Advanced tested on:Windows 11 24H2 works on:Windows 10, Windows 11 tools:Command Prompt as administrator, Windows installation USB
TL;DR

Check **reagentc /info**, re-enable the recovery environment with `reagentc /enable`, and rebuild the boot files with `bcdboot C:\Windows` from the recovery console.

Before you start

Requirements

  • Admin rights
  • A bootable Windows USB for the worst case
  • Forty-five minutes
Step by step

Instructions

01

Check whether the recovery environment exists

The tool reports enabled or disabled and where the image lives. Disabled means Advanced startup offers only what the running system can do.

reagentc /info
02

Enable it again

Windows copies its recovery image back to a suitable partition. The operation fails when the recovery partition was removed or is smaller than the image.

reagentc /enable
⚠ warningThe image needs roughly 500 MB free. A partition resized by a cloning tool is the usual reason this fails with 0x80070490.
03

Get into the recovery console while Windows still starts

One command reboots into the advanced options, where Troubleshoot gives you the command prompt that runs outside the installed system.

shutdown /r /o /t 0
04

Give the EFI partition a letter first

The system partition has no drive letter, so the boot files cannot be written until you assign one. This happens in diskpart and the letter is temporary.

diskpart, then list volume, select volume 2, assign letter=S
⚠ warningPick the FAT32 partition of 100 to 300 MB with no letter. Writing to the wrong one damages data.
05

Rebuild the boot files directly

bcdboot writes a fresh set of boot files for the Windows folder you name. It is the step that repairs a store which boot repair tools report as empty.

bcdboot C:\Windows /s S: /f UEFI
06

Verify the entry points at something real

The firmware entry names a device and a path. An entry pointing at the wrong partition boots to a black screen or straight back into firmware setup.

bcdedit /enum
Troubleshooting

Common issues

reagentc fails with 0x80070490

The recovery image is missing or the partition is too small. Recreate the partition or use a Windows USB as the recovery media.

bootrec /rebuildbcd finds no installations

Common on UEFI systems. Write the files with bcdboot instead of repairing the store.

The machine always boots into firmware setup

The boot order lost its entry. bcdboot with the UEFI switch recreates it.

The recovery console has no diskpart

It is the wrong environment. Use Troubleshoot > Command Prompt, not a recovery drive menu on a foreign USB.

FAQ

Frequently asked

Does this delete files?

No. Boot files and the recovery image change; user data and installed programs stay untouched.

Is a separate recovery partition required?

No. WinRE can also live in C:\Recovery, at the cost of space on the system drive.

How to undo this

The temporary drive letter is removed with diskpart remove letter=S. reagentc /disable removes the image placement again, which is only useful when space is the problem.

Changelog · 1 entry
  1. 2026-10-31
    First version
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