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Difficulty: MediumTroubleshooting Windows OS Startup and Boot Errors

A technician is troubleshooting a Windows workstation configured in UEFI mode that fails to start due to corrupted EFI boot files. The system has been booted into the Windows Recovery Environment (WinRE) Command Prompt to manually repair the EFI System Partition (ESP). In what sequence should the technician execute the following steps to rebuild the system boot environment?

  1. 1Run diskpart and select the main physical system disk.
  2. 2Locate the hidden FAT32 EFI System Partition and assign a drive letter to it.
  3. 3Exit diskpart and navigate to the Boot folder within the newly assigned volume.
  4. 4Execute bcdboot C:\Windows /s Z: /f UEFI to recreate the boot files.

Answer

The correct sequence begins with launching diskpart to select the target disk, assigning a drive letter to the EFI System Partition, exiting diskpart to navigate to the EFI directory, and running the bcdboot command to deploy new boot files.
To repair a corrupted EFI System Partition in UEFI mode, a technician must first open diskpart and select the main disk. Next, the hidden FAT32 EFI partition must be located and assigned a temporary drive letter. After exiting diskpart and changing to the target directory, the technician executes the bcdboot command to copy clean bootloader binaries and recreate the Boot Configuration Data (BCD) store.

Step-by-Step Solution

1
Launch diskpart and execute select disk to choose the physical OS drive.
The operating system disk is selected for partition configuration.
Before partition-level actions can be performed in WinRE, the utility must be focused on the correct disk.
2
Identify the hidden FAT32 EFI System Partition volume and assign a letter using assign letter=Z.
The EFI System Partition is mounted with drive letter Z:.
Command-line repair utilities require an active drive letter path to write updated boot files to the partition.
3
Type exit to leave diskpart, then use cd /d Z:\EFI\Microsoft\Boot\ to change directories.
The command prompt active path is positioned within the EFI boot folder.
Leaving diskpart returns the environment to standard CLI operation for file manipulation and repair commands.
4
Run bcdboot C:\Windows /s Z: /f UEFI to rebuild boot files.
Fresh bootloader binaries and a clean BCD store are generated on the EFI System Partition.
The BCDBoot tool extracts healthy boot files from the Windows directory and writes them to the specified UEFI partition.

Key Concept

Manual EFI System Partition Restoration using Diskpart and BCDBoot
Estimated Time:1m 30s
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Topics

Troubleshooting Windows OS Startup and Boot Errors

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