Repair your computer in Windows 8 and 8.1

If Automatic Repair fails and you cannot even get into Safe Mode, then most probably there are some errors or missing files on your hard disk that prevent Windows 8 or 8.1 from starting correctly. Bootable installation media (DVD or USB) or Recovery Drive/System Repair Disc are helpful in such cases.

Those who have Windows 8 or 8.1 installed on SSD, beware: turn off built-in Disk Defragmenter; there is a known bug in it that starts defragmenting (instead of using the TRIM command) SSD-s. This will lead to decreased lifetime and failure of the drive.

This is a two-page article - page 2 covers Refresh your PC, Reset your PC and restoring a system image.

Common problems with Windows 8 and 8.1 installations

Here is a list of problems that users encounter most often:

• Endless Automatic Repair failures and restart loops - you cannot disable Automatic Repair, but you can boot from installation media or Recovery Drive to fix errors and make Windows 8 or 8.1 usable again.
  The behavior can also be an indicator that Windows 8/8.1 does not have required drivers for a disk controller. You can then enterBIOS/UEFI and set your disk controller mode (aka SATA mode, RAID mode, or Intel SRT) to Standard (aka Standard IDE or SATA, Legacy) instead of AHCI or RAID (take note of the original setting first!). This will often ensure that Windows knows which drivers to use for booting from the system drive.
  In case you have multiple hard drives, power off your computer and remove its power cord. Then disconnect drive cables from all hard disks other than the one where Windows is installed. Plug the power cord back in and see if this helps Windows to boot properly.
  After Windows 8/8.1 starts, upgrade storage drivers and software using Intel's Driver Update Utility or find the driver software fromAMD's site. This often solves all problems.
  If nothing helps, boot into Recovery Environment from Recovery Drive/System Repair Disc or Windows 8/8.1 installation media, open Command Prompt and follow these instructions to disable Automatic Repair completely.
• Disk check runs each time Windows 8/8.1 starts - on multi-boot systems (Windows 8 or 8.1 is installed along with an older version of Windows or some other operating system) you need to disable the Fast Start-up feature in Shutdown settings. The feature (previously known as Hybrid Boot or Fast Boot) enables significantly shorter load times while Windows 8/8.1 starts after a shutdown or sleep/hibernation, but the file that contains fast boot information can be damaged by starting another version of Windows or another OS (Linux, for example). This causes Windows to run a disk check each time.
  Fast Start-up is available only if a user has manually enabled hibernation with the powercfg -h on command. Please note that you should never turn on hibernation if Windows is installed on SSD - this can significantly decrease the lifetime of your drive.
  To resolve the issue, open Control Panel in Windows 8 or 8.1. Type "power" into search box and click Change what the power buttons do.
  In the Define power buttons and turn on password protection window, click Change settings that are currently unavailable.
  
  Then, in the Shutdown settings section, clear the Turn on fast start-up (recommended) check box and click the Save changes button.
  
  The same setting is also often responsible for the dreaded "The drive where Windows is installed is locked" errors: after shutdown,hiberfil.sys file contains kernel session and Windows prevents any modifications to the file system to prevent possible errors. See more information about safe and unsafe fixes for hibernation-locked drives.
• Windows 8 or 8.1 is unable to boot from a GPT drive on UEFI-enabled devices - if you formatted or converted your system drive from MBR partitioning to GPT, you must ensure the EFI boot options state "UEFI only". Windows 8 and 8.1 require UEFI for GPT drives, this is a must and there is no workaround.
  In old BIOS mode, Windows 8/8.1 will not detect your GPT hard drives or partitions correctly. No booting, no Refresh Your PC or Reset Your PC until "UEFI only" is set. Credits go to Sol for confirming this issue. 
  You can easily verify whether UEFI works correctly by opening Troubleshoot and Advanced Options in Windows 8/8.1 Advanced Startup screen. If "UEFI only" is set, you'll see the UEFI Firmware Settings option listed. Thanks Sol for providing the screenshot:
  
• "The drive where Windows is installed is locked. Unlock the drive and try again" and "Unable to reset your PC. A required drive partition is missing" errors while refreshing or resetting Windows 8 or 8.1 installation, and error code 0xc000000e "A required device isn't connected or can't be accessed" while booting.
  1. First, try a cold boot. Turning off your device, remove power cord and battery (if available) and wait for about 20 seconds. Then connect battery and power cord and try booting again.
  2. These errors often indicate that file system or boot data configuration is corrupt. See how to fix errors on drives or rebuild boot information for Windows 8 and 8.1.
  3. Hibernation/Fast start-up is another cause for locked drives in Windows 8 and 8.1. Restarts do not cause this error (no hibernation file is created then), but during shutdown a hibernation-enabled device saves kernel session to a file named hiberfil.sys and prevents any further modifications to file system to keep everything intact.
  To prevent such problems, open elevated Command Prompt, type powercfg -h off and press ENTER. This disables hibernation and fast start-up/fast boot.
  See more information about safe and unsafe fixes for hibernation-locked drives.
  4. In some cases, Windows forgets the proper drive/partition order and tries to load files from a wrong one. Again, power off your computer and remove power cord. Then disconnect cables from all hard drives except the one where Windows 8 or 8.1 resides, connect power cord and see if boot process completes properly now.
  5. Or, if Windows still works somewhat, try upgrading storage drivers and software using Intel's Driver Update Utility or find the driver software from AMD's site. This often solves all problems.
• Unmountable boot volume error (Blue Screen of Death) while starting Windows.
  First, if your PC has multiple hard drives (including external USB drives!), power it off and remove its power cord. Then disconnect drive cables from all hard disks other than the one where Windows is installed. Plug the power cord back in and see if this helps Windows to boot properly.
  Second, enter BIOS/UEFI and set your disk controller mode (aka SATA mode, RAID mode) to Standard (aka Standard IDE or SATA, Legacy) instead of AHCI or RAID (take note of the original setting first!). If this one fails, try other options until Windows starts properly.
  Third, run a RAM check to verify that memory modules are working correctly. If errors are detected, reseat memory modules and re-run the check. If the tests fail repeatedly, replace or remove faulty module(s).
  Fourth, verify that hard drive/SSD SATA or IDE cables are seated properly. Unplug the cables and reseat them properly.
  Fifth, enter Recovery Environment, run Automatic Repair, and then open Command Prompt to run chkdsk.
• Unable to update firmware or drivers after push-button reset of Windows 8.1 device. This is because new value for driver or firmware dependency in Windows 8.1 cannot be handled correctly. Download and apply the patch listed in Microsoft support article KB 2913760. Windows 8.1RT users can install it using Windows Update only.
• Errors 0xc000021a and 0xc0000001 after installing latest updates for Windows. The most common cause is file system corruption, use Command Prompt to run chkdsk.
  If the error still appears after disk checks, open Command Prompt again and run DISM to revert pending actions. If DISM does not help, it is time to run chkdsk with the /R switch to verify that there are no bad clusters on your SSD or hard drive - if there are, the drive must be replaced ASAP.
   
• Errors 0xc000021a and 0xc0000001 without installing updates for Windows. If your computer has a separate partition/volume or a (micro) SSD for Intel Smart Response Technology (SRT), it might have become corrupted. Enter your device's BIOS/UEFI and change your disk controller mode from Intel SRT to SATA or AHCI. Intel Smart Response Technology might also be a separate setting in BIOS/UEFI setup, please consult your device manual on how to disable this feature.
  Also, please do not forget to run chkdsk with the /R switch - bad clusters are often the root of all evil.

Options to try before using Recovery Environment in Windows 8 and 8.1

• Always boot to Safe Mode at least once - this often repairs corrupted file system and essential system files.
• If Windows starts or runs properly only in Safe Mode, turn on Clean Boot mode to see if some third-party software or driver causes the problems.
• If Windows is able to boot, use System File Checker and icacls.exe to repair corrupted system files.
• While Windows is running, use free WhoCrashed for determining BSOD (Blue Screen Of Death) causes.
  Reliability Monitor might also reveal faulty drivers or software.
• Use Windows Update troubleshooter if your PC is unable to apply updates, or offers them repeatedly.
• In case of Windows Store apps (aka Metro UI or Modern UI apps) failing to run or update, being unstable or requiring constant repairs, clear Windows Store cache: open Start screen, type wsreset and click the result. Next, repeat the process, but right-click (or tap and hold on touch-screens) the result and choose Run as administrator. Further fixes are listed in the Fix Modern UI apps in Windows 8 and 8.1 tutorial at my other site, winhelp.info.
• Use DISM (Deployment Imaging and Servicing Management) tool to fix Windows Component Store corruption as instructed in theSystem Image Backup in Windows 8.1 tutorial - this often resolves a multitude of problems.
  In case DISM RestoreHealth command fails with error 0x800f081f, then Non-destructive reinstall of Windows 8 or 8.1 is about the only option that fixes it.

Prerequisites of Windows 8 and 8.1 Recovery Environment

If Windows 8 or 8.1 is able to start and run, you can reboot right into Recovery Environment or use the Refresh and Reset your PC options.

To access Repair your computer/Recovery Environment (aka Limited Diagnostic State), you must have either Windows 8/8.1 installation DVD or Windows 8/8.1 Recovery Drive (USB) or System Repair Disc (CD/DVD) available in case Windows is unable to start.

To put Windows 8 or 8.1 installation media onto a bootable USB drive instead, see the Create bootable Windows installation media on a USB stick guide on our sister site, www.winhelp.info. The tutorial also shows how you can download and create proper Windows 8/8.1 DVD from Microsoft if you only have product key.

If you do not have the Windows installation DVD (e.g. Windows came pre-installed) or Recovery Drive/System Repair Disc, see the instructions on creating a bootable Windows 8 or 8.1 installation media (DVD or USB).

Warning: do not use Windows 8/8.1 media for repairing Windows XP, Vista or 7 installations, or vice versa! You can only use the Command Prompt option for fixing file system errors in older Windows installations.

If you can borrow a correct Windows 8 or 8.1 installation DVD from a friend, make sure you get the right version: you can only use 32-bit (x86) Windows disc for repairing 32-bit Windows installations and 64-bit (x64) Windows disc for fixing 64-bit Windows installations.

Because Windows 8 and 8.1 Recovery Environment does not include RAM testing module, you should use Memtest86+ for checking if your computer's memory modules are fine. Please do this before using tools provided in Recovery Environment - there is no point in repairing Windows if defective memory will ruin it again soon.

The last resort is to use my Data Recovery CD/USB for fixing errors on disk or repairing Master Boot Records (MBR), but other options ofRepair Your Computer are unavailable. You can also use the CD/USB for recovering your files from the unbootable hard drive in case nothing else helps.

Getting into Recovery Environment in Windows 8 and 8.1 without installation media

In Windows 8 and 8.1, the good old F8 key trick for getting into Advanced Boot Options does not work anymore (but it can still be enabled manually). If Windows is unable to start, you can get into new Startup Settings after Windows detects it was unable to start - click See advanced repair options in Recovery screen, or after Automatic Repair fails - click Advanced options.
 

If Windows 8 or 8.1 is able to start and run, open Settings charm using keyboard shortcut WINDOWS KEY+I. The fastest way is to clickPower and then hold down SHIFT key while clicking Restart. This will reboot into Windows 8/8.1 Advanced Startup screen.
The longer way is to click Change PC settings in the bottom.

In Windows 8, click to open General tab of PC settings app, scroll all the way down to Advanced startup section and click Restart now.

In Windows 8.1, open Update & Recovery tab on the bottom left and then click Recovery tab. Click Restart now in the Advanced startup section.

This is how Windows 8/8.1 Advanced startup screen looks like.
Click Troubleshooting in Choose an option screen.
 

Booting to Recovery Environment with Windows 8/8.1 installation media or Recovery Drive/System Repair Disc

If your computer does not start from CD/DVD or USB drive, read about changing boot order.
In case of UEFI boot, look for Boot Order/Boot Priority tab or page and move CD/DVD and/or USB drive above Windows Boot Managerentry to be able to boot from media other than hard drive/SSD. You also have to connect your USB drive or insert CD/DVD before entering UEFI/BIOS Setup.
In rare cases, you might have to disable Secure Boot in UEFI/BIOS setup to boot from a USB stick or a CD/DVD.
On some Asus and HP devices, you may also need to set Launch CSM or CSM to Enabled - this turns on the Legacy/non-UEFI boot mode.
Always take note of original settings and remember to change them back after troubleshooting.

Flash drive users, please note: plug your bootable USB drive into a USB 2.0 or 1.0/1.1 port instead of a USB 3.0/3.1 (either blue in color, or has "SS" or "SuperSpeed" written near it) port if you encounter the dreaded and misleading "The requested system device cannot be found" errors here and there.

After you boot your PC using Windows DVD or System Repair Disc, a black screen appears with gray text "Press any key to boot from CD or DVD". Press some key on your keyboard (SPACE and ENTER are the most common ones ) within 5 seconds to launch Windows from the disc.
This screen will not appear while booting from USB Recovery Drive.

Windows will then load some files from the disc or drive, this takes some time.

In case you booted from Windows 8/8.1 Recovery Drive or System Repair Disc, Choose your keyboard layout screen appears. Click your keyboard layout, or if one is not visible, click the See more keyboard layouts link until you see the correct layout.

If using Windows 8 or 8.1 installation DVD, Windows Setup dialog appears. Select your preferred settings from Time and currency format and Keyboard or input method combo boxes. I suggest you leave Language to install to "English" here to better understand this article.
Click Next to continue.

Windows installation media users will then see a big tempting Install now button. Do not click it! Click Repair your computer in the lower left corner instead.

BitLocker-encrypted system drives (the drive where Windows is installed) must be unlocked first. If your device does not do this automatically using its TPM chip (startup PIN or password entry is required), you can find your BitLocker Recovery Keys athttps://onedrive.live.com/RecoveryKey (you have to sign in with your Microsoft/Windows Live/Hotmail account).
If you have a USB key for BitLocker, insert it instead.

If your device has multiple user accounts, a list of these appears next. Choose the one with administrator rights and sign in with the account's password.

Choose an option screen then appears. Click Troubleshoot.

Let's see an overview of the tools next.

Troubleshooting steps to take in Windows 8 and 8.1 Recovery Environment

Please note that if you are using a wrong media here - e.g. Windows 7 installation DVD on Windows 8 PC, or 32-bit version of Recovery Drive/System Repair Disc on 64-bit Windows - you can use the Command Prompt option only to run chkdsk/file system check. While the other options are not disabled in the list, using these end with error messages and might damage your broken Windows installation even more.

Step 1 - Automatic Repair and Startup Repair in Windows 8 and 8.1

Unless you started Windows 8/8.1 Recovery Environment from a failed Automatic Repair attempt, the very first option to try in case Windows is unable to boot is the Automatic Repair (in Windows 8) or Startup Repair (Windows 8.1) that will check the condition of your hard disk and see if files needed to launch Windows are present. The process takes from a few seconds to half an hour, depending on the problem.
Automatic Repair/Startup Repair can be used to fix file system corruption and Boot Configuration Data issues (for example, the0xc000000f "The Boot Configuration Data for your PC is missing or contains errors" and 0xc0000034 "Boot Configuration Data file missing required information" errors).
To access the option, click Advanced options in Troubleshoot screen.

In the Advanced Options screen, click Automatic Repair or Startup Repair.
 

Next, choose a target operating system by clicking on its button. In most cases, you should have only one Windows 8 or 8.1 installation visible.

Windows will then look for problems on hard drive(s) and verify that all required files are intact. This might easily take 10 or more minutes. Please stand by.

In case Automatic Repair was unable to fix problems, click Advanced options to access other recovery tools.

If repairs were successful, your PC will restart automatically.

Step 1.1 (optional) - use Command Prompt for fixing disk errors, restoring missing system files, reverting pending updates, or preventing Automatic Repair from launching

To fix file system errors, click Command Prompt in the Advanced Options screen. This also helps in case of error 0xc000021a that might appear after installing the latest updates - the most common cause for this is file system corruption.

A black Command Prompt window opens on drive with letter X. It is a special temporary disk created entirely in the Random Access Memory (RAM) of your PC. No hard disk space is used for this drive.
First, we need to locate the drive where Windows is installed. Most probably this is a drive with letter C, D, E or F.
Type echo list volume | diskpart and press ENTER. This will display all drives/volumes/partitions available. You need to use this command to verify that no partition/volume is listed as having RAW file system type.

Ignore all volumes that have "CD-ROM" written in Type column.
The volume that has "System Rese" (part of "System Reserved") written in Label column, is the recovery partition, and it typically has drive letter C in Ltr column. Such partitions are usually small in size - about 300 to 350 megabytes (MB). You should check this partition for errors, because normally Boot Configuration Data (BCD) is stored there.
Please note that not all computers have the recovery partition.

So, in the example above, the Windows 8 partition has drive letter D (note the Ltr column). You can also use the Size column for verifying that you have located the correct one. Do not mix up megabytes (MB) and gigabytes (GB).

To double-check the Windows drive letter, type bcdedit | find /i "OSDEVICE" and press ENTER.
This outputs something like osdevice partition=E: where the very last letter is your Windows/system drive letter. It might be some other letter in your case.

In case your Windows partition showed up as RAW in Fs (File System) column, you still need to run chkdsk and take note of the results. Normally, Windows partition should list "NTFS" in Fs column.

Do note that third-party disk encryption (such as TrueCrypt, VeraCrypt, etc) can also make file system appear as RAW. This means that you must decrypt the drive or partition/volume first.

Now type chkdsk <the drive letter>: /F /X and press ENTER. Replace <the drive letter> with the letter of drive where Windows is installed (or the drive that has files badly messed up), for example chkdsk d: /F /X or chkdsk c: /F /X.
This command will find and repair errors on the partition/volume (the /F switch) and if required, unmount it first (the /X switch).

If you want to run a full disk check with recovering data from unreadable clusters, use the chkdsk <the drive letter>: /R /Xcommand instead. This is a must in case of repeating error 0xc000021a. Note that the exhaustive test might take several hours to complete.
In case you see a lot of errors about bad clusters, your hard drive is about to fail completely. Backup your files either by using Puppy Linux, or by putting the faulty drive in an external drive enclosure/another PC (this is for experts only).

The process might take quite a while (up to an hour without the /R switch, and several hours with the /R switch). After it is completed, verify that there is a line stating "Windows has checked the file system and found no problems" in the report.
If there were errors on the volume, repeat the last command (press ARROW UP key to recall the last command) until the no problems message appears.

Please check other partitions, especially the 300-450 MB "System Rese" one for errors, too. If you have more than one hard drive installed or more than two volumes/partitions, do not forget to run disk check on these - this might solve your problems.

If Windows partition was listed as RAW in diskpart and you see the "A disk read error occurred c0000185" message before chkdsk completes, you need to either reseat or replace hard drive cable (turn off your PC, disconnect power cord, then unplug and replug theSATA cable both on motherboard side and hard drive/SSD side). If your PC case is very dusty inside, clean it with compressed air before reseating or replacing the cable.
Another method that works surprisingly often in this case, is resetting BIOS/UEFI to defaults. Reboot your PC and press F1, F2, F10,F12 or DEL (aka DELETE) key to get into BIOS/UEFI (the correct key is usually displayed on screen first). On some computers you might have to press ESC key to see options list. Then find and use the option that is similar to "Restore defaults" or "Load defaults". Intel motherboards have F9 key for this purpose.
Please note that you might encounter the "Windows failed to start, File: \Boot\BCD, Status: 0xc000000f, Info: The Boot Configuration Data for your PC is missing or contains errors" screen after resetting BIOS to defaults. This can be easily fixed with Automatic Repair/Startup Repair or bootrec as shown here.
If reseating/replacing SATA cable and resetting BIOS/UEFI to defaults does not help, run Memtest86+ to verify that RAM modules are working correctly. If a RAM module has errors, remove or replace it.

Ignore any failure messages about event log: this is because event logs are not available in Recovery Environment.

After chkdsk repairs file system errors on all volumes, close Command Prompt by clicking the X mark on the top right. Click Continue in the Choose an option screen to try starting Windows normally and see if the problem has been solved.
If no disk errors were found, read on.

Recover missing or corrupted system files with SFC

You can also try restoring missing system files using the SFC (System File Checker) tool. This is useful in cases where Windows boots up, but all you see is black screen with mouse pointer and keyboard shortcut CTRL+ALT+DEL does nothing.

Type sfc /scannow and press ENTER. Let the scan finish, it will take about half an hour.

If you see the error message "There is a system repair pending which requires reboot to complete. Restart Windows and run sfc again.", use alternative command sfc /scannow /offbootdir=C:\ /offwindir=D:\ (replace D:\ with the correct drive letter for your CD/DVD or USB drive if necessary).

Fix error 0xc000021a with DISM

If disk check did not resolve error 0xc000021a, you need to revert pending updates using DISM.
First, check the letter for the drive where Windows is installed using bcdedit | find /i "OSDEVICE" command.
Then type dism /image:D:\ /cleanup-image /revertpendingactions (replace D:\ with the correct drive letter for your Windows drive) and press ENTER. Ignore any error messages about scratch directory size.

Another reason for error 0xc000021a is often a corrupted partition or SSD dedicated to Intel Smart Response Technology (aka Intel SRT). Enter your device's BIOS/UEFI setup and change your disk controller mode from Intel SRT to SATA or AHCI. Intel Smart Response Technology/SRT can also be a separate setting in BIOS/UEFI setup, please consult your device manual on how to disable this feature.

Please do not forget to run chkdsk with the /R switch if DISM did not help. For example, to fully check drive D:, type chkdsk D: /R /X . This exhaustive, several-hour test will check for bad clusters and try to recover data from those. If there are bad clusters on the drive, you need to replace it as soon as possible - it can only get only worse.

One safe and one unsafe fix for the "drive where Windows is installed is locked" error (works ONLY when hibernation has been enabled)

If you cannot repair Windows 8 or 8.1 because of "The drive where Windows is installed is locked, Unlock the drive and try again" error,and you or someone else has turned on hibernation/fast start-up/hybrid boot in Windows, there are two ways of working around it.

The safe option works only if Windows is able to boot normally or into Safe Mode. Open Start screen, type cmd, right-click the result and choose Run as administrator. This will open elevated Command Prompt.
Type powercfg -h off and press ENTER key. Restart your computer and retry whatever you were trying to do.

The second, unsafe option works even when Windows refuses to boot due to the "drive is locked" error. This is unsafe because it deletes the hiberfil.sys file that contains kernel session (used RAM and loaded drivers) from the last time Windows actually ran and was shut down. Deleting this file can create a few minor problems if you last hibernated your device (instead of choosing Shut Down), but it might be the only way to continue troubleshooting. A side note: if you are lucky, no problems appear at all, so it is a bit like "well, you should not quite do that, but ok" solution.

In Command Prompt, type bcdedit | find /i "OSDEVICE" and press ENTER.
This outputs something like osdevice partition=E: where the very last letter (E: in this case) is your Windows/system drive letter. It might be some other letter in your case.

Type dir <Windows/system drive letter from previous step>:\ /ah , for example dir E:\ /ah and pressENTER. This lists all files with attribute called "Hidden" in the root folder of system drive.
Verify that hiberfil.sys is listed. If not, then make sure you used the correct drive letter. When the drive letter really is correct, hibernation is not enabled and there is not point in continuing with this solution.

If the file is there, count your prayers, type del <Windows/system drive letter>:\hiberfil.sys /ah , for example del E:\hiberfil.sys /ah and press ENTER.

Close Command Prompt and retry booting Windows. You might encounter several errors, but if Windows starts, you've resolved the dreaded "drive is locked" error. Please do follow the first, safe solution of running powercfg -h off to prevent the same error from appearing again.

Prevent Automatic Repair loop

If your Windows 8 or 8.1 PC is stuck in Automatic Repair loop, try disabling the feature via Command Prompt. Type bcdedit /set {default} recoveryenabled NO and press ENTER Key. If the message reads "The operation completed successfully", then Automatic Repair will not appear until you re-enable it with the bcdedit /set {default} recoveryenabled YES command in an elevated Command Prompt.

Close Command Prompt window and and click Continue to see if this helped to get your Windows 8 or 8.1 PC running correctly again.

Step 1.2 (optional) - temporarily enable the F8 key for getting into Advanced Boot Options menu at computer startup

Because Windows 8 and 8.1 have no support for F8 key by default, you might be unable to get into Safe Mode or Low-resolution video mode for troubleshooting unless Windows starts properly. Somehow Microsoft couldn't foresee this vicious circle happening to many users.

Luckily, you can enable the good old trick in the Command Prompt window described in Step 1.1 above. Please note that legacy boot options should not be turned on forever because they can cause trouble on UEFI systems. This is just a temporary workaround.

In the black Command Prompt window, type bcdedit /set {default} bootmenupolicy legacy and press ENTER key. You should see "The operation completed successfully" message after this.

Close Command Prompt window and restart your computer. Pressing F8 key repeatedly before Windows 8 or 8.1 starts loading should now bring up the older Advanced Boot Options menu.

To revert to the newer Modern UI version of troubleshooting tools, open elevated Command Prompt while Windows is running (use WINDOW KEY+X to open Quick Links menu and click Command Prompt (Admin)). You can also boot from Windows installation media or System Repair Disc/Recovery Drive and open Command Prompt in Recovery Environment.
Type bcdedit /set {default} bootmenupolicy standard and press ENTER key.

Close the Command Prompt window and reboot your PC. Now your computer uses the Modern UI boot options again.

Step 1.3 (optional) - repair Boot Configuration Data with bootrec (please read the warning first!)

If Windows 8 or 8.1 BCD (Boot Configuration Data) becomes corrupt after a crash, power outage or some other reason, you'll encounter the "The drive where Windows is installed is locked. Unlock the drive and try again" and "Unable to reset your PC. A required drive partition is missing." errors while refreshing or resetting Windows 8 or 8.1 installation, and error code 0xc000000e "A required device isn't connected or can't be accessed", 0xc0000001 "A required device isn't connected or can't be accessed", 0xc000000f "The Boot Configuration Data for your PC is missing or contains errors" or 0xc0000034 "Boot Configuration Data file missing required information" while booting.

Please note that all partitions must be listed as NTFS or FAT32 in Fs column of echo list volume | diskpart results, otherwise there is no point in running the following commands. If you run the following commands on RAW file system, you might kill boot sector data and end up with a computer that is unrepairable! Sure signs of a completely messed up drive are errors "The first NTFS boot sector is unreadable or corrupt" and "Unable to determine volume version and state. CHKDSK aborted." while running disk check.

Please note that third-party disk encryption (such as TrueCrypt, VeraCrypt, etc) can also make file system appear as RAW. This means that you must decrypt the drive or partition/volume first.

If you came here from another website, then please note that bootrec is only available in Windows RE (Recovery Environment), not while Windows is running normally: please read the Booting to Recovery Environment with Windows 8/8.1 installation media or Recovery Drive/System Repair Disc section if Windows is not able to boot and run normally, or the Getting into Recovery Environment in Windows 8 and 8.1 without installation media section if Windows starts and runs properly (you are probably here to resolve the Windows 10 installation failing at 24% trouble).

This is your final warning: you must type echo list volume | diskpart , press ENTER key and verify that no volumes have RAW listed in Fs column before trying the bootrec commands. In case even one volume or partition is listed as RAW, stop now and see howchkdsk results can sometimes reveal the cause for Windows partition listed as RAW.

Did you actually read the warning above and verified volume file system types? Then type the following commands and press ENTER after each one:

• bootrec /fixmbr (not necessary if your device is in UEFI Only mode)
• bootrec /fixboot
• bootrec /rebuildbcd

If you see a prompt to add one or more detected Windows installations after the last command, press A and then ENTER on keyboard. This means that BCD has been fixed successfully: close Command Prompt and restart your PC.

In case the rebuildbcd command results in "The requested system device cannot be found" error, you probably have plugged your bootable USB drive into a USB 3.0/3.1 port (color blue, or "SS/SuperSpeed" written near it). Shut down your computer, plug your drive into a USB 2.0 port and retry.

But in many cases, the bootrec /rebuildbcd command results in 0 total identified Windows installations instead. The screenshot below illustrates this situation:

To resolve this problem, you first need to locate the drive where Windows Boot Manager resides. In Command Prompt window, typebcdedit and press ENTER. Locate the entry Windows Boot Manager (usually the very first entry with identifier {bootmgr}) and see the second line, device. In this example, the line reads "partition=C:", meaning that Windows Boot Manager is on the partition/volume with drive letter C. In many cases, the drive letter might be something different.

Run the following commands in case your PC is in legacy boot mode (uses BIOS, or is set to legacy boot). If necessary, replace drive letter "C" with the previously detected drive letter in the first two commands.
If the first command fails with "Path not found" error, your PC is not in legacy boot mode, or you used a wrong drive letter. Do not worry, try the UEFI boot mode commands instead, or double-check the drive letter from bcdedit output.

• cd /d C:\Boot\ (if this command fails, your PC is probably in UEFI boot mode)
• attrib C:\Boot\BCD -h -r -s (removes hidden, read-only and system attributes from BCD folder)
• ren C:\Boot\BCD BCD.old (renames BCD folder to BCD.old)
• bootrec /rebuildbcd (retries the rebuild)

In case your computer is in UEFI boot mode (the commands above resulted in "The system cannot find the file specified" error), use the following commands instead:

• diskpart (opens Disk Partitioning tool)
• select disk 0
• list volume (please note the number of the volume that has no drive letter assigned and has FAT32 listed in Fs column, usually the only FAT32 volume/partition)
• select volume <the number of 100-500 MB FAT32 volume with no drive letter, or with label ESP, EFI or SYSTEM>
• assign letter=Z: (gives drive letter Z: to EFI System Partition)
• exit (closes Disk Partitioning tool)
• cd /d Z:\EFI\Microsoft\Boot\ (changes current folder in Command Prompt window)
• attrib Z:\EFI\Microsoft\Boot\BCD -h -r -s (removes hidden, read-only and system attributes from BCD folder)
• ren Z:\EFI\Microsoft\Boot\BCD BCD.old (renames BCD folder to BCD.old)
• bootrec /rebuildbcd (retries the rebuild)

Now, in the Add installation to boot list line, type A and press ENTER. The new BCD is ready, close Command Prompt and restart your computer.

Step 2 - System Restore

The next step is to try System Restore from Advanced Options screen. This works only while using the correct Windows installation or System Repair Disc. Using Windows 7 media on Windows 8/8.1 installation (or vice versa) ends with an error message about no available Restore Points.

System Restore will literally turn back time for your PC: while your documents and files will always remain intact, all programs or drivers installed after the selected Restore Point might disappear and must be reinstalled. Also, if you changed your Local Account password recently, it might be reverted to the previous one by the selected Restore Point.
Please note that this System Restore cannot be undone (but you can still restore another Restore Point later).

Read detailed instructions on using System Restore in this article.

Move on to the next page of this article to read about Refresh your PC, Reset your PC and re-imaging options.