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Windows laptop on a dark desk displaying a blue screen Boot Configuration Data missing error code 0xc0000034 in a dimly lit home office
Fix It Yourself · Troubleshooting

Boot Configuration Data missing on Windows

Updated 6 November 202612 min read
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Your PC stops at a blue or black screen saying the Boot Configuration Data for your PC is missing or contains errors, often with 0xc000000f or 0xc0000034. Your files are usually still there. Start with Windows' own repair. If that fails, you can rebuild the boot files by hand, once you know which commands fit your PC.

What Causes Boot Configuration Data Missing?

The Boot Configuration Data (BCD) store is a small database Windows Boot Manager reads every time the PC starts. It says which Windows to load and where it is. Where it lives depends on how the disk is set up. On a UEFI PC with a GPT disk, it's in the EFI System Partition (ESP), a small hidden FAT32 partition. On an older BIOS PC with an MBR disk, it's in a Boot folder on the active system partition. That difference changes the repair, and fix 5 shows how to tell which you have.

An interrupted write. A power cut, a forced shutdown or a crash during an update can leave the BCD or the boot files damaged.

Disk and partition changes. Cloning to a new drive, resizing or deleting partitions, or removing a second drive that happened to hold the ESP can leave Windows with no boot entry it can use.

The wrong boot disk. A USB stick, memory card or second drive first in the boot order can bring up the same message, because the PC is trying to start from the wrong place.

A failing drive. Bad sectors can damage boot files. If the drive clicks, disappears from the firmware's boot list, or the error comes back after every repair, treat it as a hardware problem and get your data off first.

Two codes often go with this error: 0xc000000f and 0xc0000034. Both mean Windows Boot Manager couldn't read a usable boot entry. Microsoft's documentation on BCD system store settings describes what the store holds.

BitLocker first. If the drive is encrypted with BitLocker or Device Encryption, recovery tools may ask for the 48-digit recovery key before they can touch Windows. Get it now from another device at aka.ms/myrecoverykey, signed in with the Microsoft account used on the PC, or from your workplace's IT team if it's a work PC.
Quick routeStart here

Boot Configuration Data Missing: Quick Fix

Start with the boot order and Windows' own repair. Neither changes your files.

1

Remove Extra Drives and Check the Boot Order Easy

  1. Unplug everything you don't need.
    Remove USB sticks, memory cards, external drives and docks, then restart.
  2. Check what the PC boots from.
    Open the firmware settings (often F2, Del or F10 at power-on, depending on the maker) and make sure Windows Boot Manager, or the drive Windows is on, is first in the boot order. Save and restart.
If Windows starts, the PC was trying to boot from the wrong drive. Keep that drive lower in the boot order.
2

Run Startup Repair Easy

  1. Get into the recovery environment.
    If Windows fails to start twice in a row, it usually opens Automatic Repair on the next start. If it doesn't, boot from Windows installation media, choose your language, click Next, then select Repair my PC and click Next to enter the recovery environment. On older media it may be called Repair your computer. Don't select Install Windows.
  2. Run it.
    Go to Troubleshoot > Advanced options > Startup Repair and pick your Windows installation if asked. Let it finish.
  3. Restart.
    If the error comes back, carry on below.
No installation media? On a working PC, use Microsoft's Windows 11 download page to create a bootable USB stick of at least 8 GB. Everything on the stick is erased.
Intermediate routeKeep going if needed

More Boot Configuration Data Missing Solutions

These are still menu-driven. Use them if the error started after an update or a change you made.

3

Uninstall the Latest Update Easy

  1. Open the option.
    In the recovery environment, go to Troubleshoot > Advanced options > Uninstall Updates.
  2. Remove the latest one.
    Choose Uninstall latest quality update first. If the problem started after a big version upgrade, try Uninstall latest feature update instead. Your files stay as they are.
4

System Restore Easy

  1. Open System Restore.
    Go to Troubleshoot > Advanced options > System Restore.
  2. Pick a point from before the problem.
    The wizard can show which programs and drivers will be affected. Your documents and photos aren't changed, but apps installed since then are removed.
  3. Let it finish.
    Don't switch off while it runs. If there are no restore points, go on to the advanced fixes.
Advanced routeChange one thing at a time

Advanced Boot Configuration Data Missing Fixes

Everything from here runs in the recovery environment's Command Prompt (Troubleshoot > Advanced options > Command Prompt), and the commands differ between UEFI and BIOS PCs, so fix 5 finds out which you have before anything is rebuilt.

5

Find Your Windows Drive and Boot Partition Medium

  1. Find the Windows disk.
    Type diskpart, then list volume. Find the likely Windows volume by its size and label, then type select volume N and detail volume. Note the disk number it shows, type select disk N, then list disk. A star in that disk's Gpt column means the Windows disk uses GPT.
  2. Find the boot partition.
    Type list volume. On a GPT Windows disk, select a small FAT32 volume marked System with select volume N, then detail volume, and make sure it's on the Windows disk. Then type assign letter=S. If the Windows disk has no EFI System Partition, stop there. Don't use a FAT32 partition on another disk or try to create one from this guide, and get help before changing partitions. On an MBR disk, the boot partition is the System Reserved partition, or the Windows partition itself. If System Reserved has no drive letter, select it and type assign letter=S.
  3. Leave DiskPart.
    Type exit before checking the Windows drive below.
  4. Check the Windows letter.
    Type dir C:\Windows. If that isn't found, try dir D:\Windows and so on. Use that letter in place of C: below.
  5. If the drive is still locked.
    If the recovery environment asks for the recovery key, enter its 48 digits. If dir C:\Windows says Access is denied instead, the drive is still protected by BitLocker. Microsoft's manage-bde reference gives the command that opens it with your key, from this same Command Prompt.
6

Rebuild the Boot Files on a UEFI PC with bcdboot Hard

  1. Write fresh boot files and a new BCD.
    This writes a new BCD store on the ESP, so check the Windows drive and ESP one more time. If you aren't certain you selected the right ones, stop and get help. Then type bcdboot C:\Windows /s S: /f UEFI, using your Windows letter and the letter you gave the ESP. It should say Boot files successfully created.
  2. Restart.
    Type exit, close the window and choose Continue. If the firmware lists more than one Windows Boot Manager, pick the one on the drive Windows is on.
On UEFI PCs, bootrec /fixboot often fails with Access is denied. That's expected, and bcdboot is the right tool here. Microsoft's bcdboot reference explains the options.
7

Rebuild the BCD on a BIOS (MBR) PC with bootrec Hard

  1. Set the active partition first.
    This is for MBR disks only, never GPT. In DiskPart, type select disk N, using the Windows disk number you identified above, then list partition. Once you've confirmed which is the System Reserved partition (or the Windows partition, if there isn't one), type select partition N and active. Marking the wrong partition active can stop Windows starting, so don't guess.
  2. Repair the boot code and scan.
    If this PC also starts Linux or another operating system, stop here and get help first, because bootrec /fixmbr replaces the MBR boot code and can remove that operating system's boot menu. Otherwise run bootrec /fixmbr, bootrec /fixboot, then bootrec /scanos.
  3. Rebuild.
    Run bootrec /rebuildbcd. If it finds your Windows, type Y to add it.
  4. If rebuilding still doesn't work.
    First run copy /b S:\Boot\BCD C:\BCD_Backup, replacing S: with the letter of the partition that holds the Boot folder and C: with a writable drive with free space. Continue only if the copy succeeds. Then set the old store aside and rebuild: attrib S:\boot\bcd -h -r -s, then ren S:\boot\bcd bcd.old, then bootrec /rebuildbcd again. If the backup fails or bootrec /scanos finds no Windows installation, stop and recheck the Windows drive, BitLocker and the boot partition before renaming anything.
Microsoft's advanced boot troubleshooting guide covers these steps in more detail.
8

Check the Drive for Errors Medium

  1. Back up first if you can.
    If the drive might be failing, copy your files off before running a long scan. A full scan reads every sector and puts more strain on a weak drive.
  2. Fix file system errors.
    Run chkdsk C: /f. If it reports problems it can't fix, or you suspect bad sectors, run chkdsk C: /r, which takes much longer.
  3. Rebuild again.
    If chkdsk fixed errors, repeat fix 6 or 7.
9

Reset or Reinstall as a Last Resort Medium

Get your files off first, for example by connecting the drive to another computer with a USB adapter and copying them. A reset removes your apps, and a clean install wipes the partitions you install over.
  1. Reset this PC.
    In the recovery environment, go to Troubleshoot > Reset this PC > Keep my files. It reinstalls Windows and keeps personal files in your user folders, but removes your apps.
  2. Clean install.
    If the reset fails, a clean install from installation media creates new boot files, but erases the partitions you install over.
When to stop. Stop running repairs if the drive clicks, keeps disappearing from the firmware, or chkdsk finds new bad sectors each time. Those are signs of a failing drive, and getting your data off comes first. If the drive needs replacing after that, our storage buyer's guide covers SSDs that suit a Windows system drive.

For IT Pros: Boot Configuration Data Missing on Managed PCs

  1. Have the recovery key ready.
    For an Intune-managed device, go to Devices > All devices > [device] > Monitor > Recovery keys, then select Show Recovery Key. For a Microsoft Entra-joined device, open the device in Microsoft Entra admin center and select Show Recovery Key. The key is there only if it was backed up to the service. On domain-joined PCs it may be backed up to Active Directory.
  2. Read the target store before you change it.
    From the recovery Command Prompt, name the store instead of relying on the recovery environment's default. On UEFI, run bcdedit /store S:\EFI\Microsoft\Boot\BCD /enum all. On BIOS, run bcdedit /store S:\Boot\BCD /enum all. Replace S: with the letter of the boot partition. Check device and osdevice against the partitions you identified. If either shows unknown, stop and verify the store and partitions before editing them.
  3. Check WinRE after the repair.
    Once Windows starts, run reagentc /info from an elevated Command Prompt and make sure Windows RE is enabled, so its recovery tools are available if you need them.

Preventing Boot Configuration Data Missing

A few habits make this far less likely to come back.

  • Let updates finish. Don't hold the power button while Windows is installing updates. If power cuts are common where you are, a UPS protects a desktop during writes.
  • Keep a recovery USB. Make Windows installation media now, while the PC works, and keep it somewhere you'll find it.
  • Keep your BitLocker key somewhere safe. Check it's in your Microsoft account, or print it.
  • Leave the small partitions alone. Don't delete or move the EFI System Partition or System Reserved partition with a partition tool, and be careful when cloning to a new drive.
  • Watch the drive's health. If Windows reports disk errors, back up and check the drive before it fails.

Boot Configuration Data Missing: Summary

A Boot Configuration Data missing error stops Windows starting, but your files are usually intact. Remove extra drives and check the boot order, run Startup Repair, and if the error began after an update, uninstall it or use System Restore.

If those fail, find out how your disk is set up, enter the BitLocker recovery key if asked, and rebuild the boot files: bcdboot on a UEFI PC, bootrec on a BIOS PC. If the drive might be failing, get your data off before running chkdsk. Back up before a reset or reinstall too. If chkdsk keeps finding new bad sectors, treat the drive as failing and replace it.

Frequently Asked Questions

Windows Boot Manager couldn't read a usable entry in the Boot Configuration Data store, the small database that tells it how to start Windows. Your files are usually still on the drive. The error often shows with the code 0xc000000f or 0xc0000034.

Sometimes. If Windows fails to start twice, it usually opens Automatic Repair, where Startup Repair, Uninstall Updates, System Restore and Command Prompt are under Troubleshoot > Advanced options. If the recovery environment won't open, you'll need Windows installation media made on another PC.

It only adds Windows installations it finds to the boot list and doesn't touch your files. This guide uses it for BIOS (MBR) PCs. On a UEFI PC, rebuilding the boot files with bcdboot is usually the better route. If the drive uses BitLocker, have the recovery key ready.

No. It doesn't change documents, photos or other personal files, but it removes apps, drivers and updates installed after the restore point you pick.

Get your data off before anything else, especially if the drive clicks or chkdsk keeps finding new bad sectors. Then try Reset this PC with Keep my files, which removes your apps, or a clean install, which erases the partitions you install over. A drive that's failing needs replacing first.