Windows won’t start

Boot Configuration Data (BCD) is missing or corrupted

Windows shows an error mentioning the Boot Configuration Data file is missing or contains errors, preventing startup. The BCD is a small file that tells the PC how to find and load Windows.

Difficulty
Advanced
Time
30–90 minutes
DIY cost
$0
Pro cost
$100–$200

Symptoms

  • Error message specifically mentions Boot Configuration Data or BCD
  • May include a status code and info line about the file
  • PC doesn't proceed to the Windows logo
  • Often follows a failed update, disk partition change, or improper shutdown during an update

Likely causes

  • CommonBCD file corrupted by an improper shutdownInterrupting a system update or shutdown at the wrong moment can damage this small critical file.
  • CommonPartition changes affecting the boot partitionResizing, deleting, or reformatting partitions near the boot partition can break the BCD's references.
  • PossibleMalware or antivirus tools that modified boot filesAggressive malware removal occasionally damages legitimate boot files as a side effect.
  • PossibleMulti-OS or dual-boot conflicts overwriting BCD entriesInstalling another OS afterward can overwrite Windows's boot configuration.
  • Less commonFailing drive corrupting the BCD sectorPhysical drive issues can corrupt this data along with other files.

What to do

  1. Boot from a Windows installation USB and choose Repair your computer, then open Command Prompt from Advanced options.
  2. Run 'bootrec /rebuildbcd' first; if it finds Windows installations, follow the prompts to add them.
  3. If that doesn't fully resolve it, run 'bootrec /fixmbr' followed by 'bootrec /fixboot'.
  4. If bootrec commands report errors, back up the existing BCD store, then try manually rebuilding it with 'bcdedit' commands referencing your Windows partition.
  5. Run 'chkdsk C: /f' to rule out underlying disk corruption contributing to the problem.
  6. If a dual-boot setup caused this, boot the other OS's installer or recovery tool to restore its boot loader properly, then run Windows's bootrec commands afterward to re-add Windows's entry.
  7. If BCD repair repeatedly fails, back up personal files where possible and consider a clean Windows reinstall.

Tools and parts

  • Bootable Windows installation USB drive

When to call a pro

If bootrec and bcdedit commands don't resolve the BCD error and you're not comfortable with manual boot loader repair, a technician can rebuild it or perform a repair install for you.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.