Windows Boot Error 0xC0000034 — Missing Boot Configuration Data

Overview

Windows boot error 0xC0000034 means the Boot Configuration Data (BCD) file is missing or corrupted, preventing Windows from starting.

Key Details

• Error 0xC0000034: 'Windows could not start because the BCD file is missing or corrupt'
• BCD (Boot Configuration Data) is the modern replacement for boot.ini
• Stored on the EFI System Partition (ESP) for UEFI or the active partition for Legacy BIOS
• Can be caused by disk errors, failed updates, or dual-boot configuration changes
• Requires Windows Recovery Environment or installation media to fix

Common Causes

• BCD store file deleted or corrupted by disk error
• Failed Windows Update corrupting boot files
• Dual-boot configuration changes damaging the BCD
• Disk cloning or partition resizing affecting the boot partition
• Malware targeting boot configuration files

Steps

1. 1Boot from Windows installation USB/DVD > Repair your computer > Command Prompt
2. 2Run: bootrec /fixmbr (Legacy BIOS) or bootrec /fixboot (both)
3. 3Rebuild BCD: bootrec /rebuildbcd — scan and add Windows installations
4. 4If rebuildbcd fails: bcdedit /export C:\bcd_backup && ren C:\boot\bcd bcd.old && bootrec /rebuildbcd
5. 5For UEFI: bcdboot C:\Windows /s S: /f UEFI (where S: is the EFI partition)

Tags

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Frequently Asked Questions