How to Fix Error Code 0xc0000034 (Boot Configuration Data Missing)

By ErrorFix · Updated October 13, 2026 · 9 min read

What error 0xc0000034 means

The full message on the blue screen reads something like: "Your PC needs to be repaired. The Boot Configuration Data file is missing some required information. File: \BCD. Error code: 0xc0000034." In technical terms, Windows keeps a small file called the BCD (Boot Configuration Data) that tells the boot loader exactly how to start the operating system — which drive holds Windows, which boot entry to use, and which language and options to load. With 0xc0000034 the file itself is usually there, but one or more of the entries Windows requires is missing, so the boot process cannot continue.

This is a boot-time error, not a Windows-is-running error, so you cannot fix it from inside Windows — you need the recovery tools that run before Windows loads. It shows up most often after a Windows upgrade or clean install that didn't finish cleanly, which is why people frequently see it after an update. The reassuring part is that your files are almost always untouched: the damage is confined to the boot data, and once it is rebuilt, Windows usually starts right back up with everything intact. Nothing in the steps below deletes your data.

Common causes

• Interrupted Windows upgrade or installation: the most common cause. If a power cut, forced shutdown, or failed install step stops the upgrade while it is rewriting the boot files, the BCD ends up incomplete.
• Corrupted boot files from disk errors: bad sectors on the system partition can damage the BCD, stripping out required entries and producing this error on the next start.
• Cloning Windows to a new SSD without repairing the boot files: disk-cloning tools copy the Windows partition but don't always rebuild the BCD correctly, leaving the cloned drive with a BCD that is missing required information.
• Partition changes after dual-booting: resizing, deleting, or reordering partitions — especially removing a Linux partition — shifts partition numbering and breaks the references the BCD depends on.
• Malware or failed boot-repair attempts: bootkits that tamper with the boot chain, or a previous boot-repair tool that wrote an incomplete BCD, can both leave the file missing required entries.

How to fix error 0xc0000034 — step by step

Work through these fixes in order. Steps 1 through 4 resolve the error for the large majority of PCs.

1. Boot into the Windows Recovery Environment. If your PC already reaches the blue "Your PC needs to be repaired" screen, the tools may already be there. If not, create a Windows 10 or 11 installation USB on another computer using Microsoft's Media Creation Tool, plug it into the failing PC, and boot from it (usually by pressing F12, F9, or Esc during startup and choosing the USB drive). On the first setup screen choose your language, then click Repair your computer in the bottom-left corner. Go to Troubleshoot, then Advanced options, then Command Prompt.
2. Run Startup Repair first. From the Advanced options screen, choose Startup Repair and select your Windows installation. Let it scan and attempt automatic repairs — it sometimes fixes an incomplete BCD on its own. If Startup Repair succeeds, restart and you are done. If it fails or reports it can't fix the problem, go back to Advanced options and open Command Prompt.
3. Rebuild the boot records with bootrec. In Command Prompt, type bootrec /fixmbr and press Enter to rewrite the master boot record, then bootrec /fixboot and press Enter to write a new boot sector. If /fixboot reports "Access is denied," skip it for now — Step 5 handles UEFI systems. Then type bootrec /scanos and press Enter to find your Windows installations, followed by bootrec /rebuildbcd and press Enter. When it asks whether to add an installation to the boot list, type Y and press Enter.
4. Recreate the BCD with bcdboot. Type bcdboot C:\Windows /l en-us and press Enter. This builds a completely fresh BCD from your Windows installation, filling in the required information that is missing. If your Windows drive has a different letter in the recovery environment (check with diskpart, then list volume), replace C: with the correct letter. The /l en-us flag sets the boot language explicitly, which matters for this error.
5. Reinstall the UEFI bootloader if needed. On UEFI PCs where the error persists, the EFI system partition itself needs a fresh boot entry. In Command Prompt, run diskpart, then list volume, and note the small FAT32 partition labeled as EFI or ESP. Run select volume N (using its volume number), then assign letter=Z, then exit. Finally run bcdboot C:\Windows /s Z: /f UEFI to write a fresh boot entry directly to the EFI partition.
6. Check the disk and repair system files. If the error still persists, reopen Command Prompt from Advanced options and run chkdsk C: /f /r to find and repair disk errors — this can take a while on large drives. After that completes, run sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows to repair corrupted system files from outside Windows, then restart once more.

Did this fix it? Quick checklist

• The PC boots past the blue recovery screen to the Windows sign-in screen
• No "Boot Configuration Data file is missing some required information" message appears
• bootrec and bcdboot reported success with no errors in Command Prompt
• The PC restarts cleanly a second time with no USB drive plugged in

If Windows boots but the error returns after a few restarts, run a health check on the drive — repeated BCD damage is a classic sign of a failing hard drive or SSD. You can also try System Restore from Advanced options to roll back to a point before the error appeared. As a last resort, choose Reset this PC from Troubleshoot and pick Keep my files: it reinstalls Windows while preserving your personal data.