Troubleshooting Boot Errors with BootRec Commands When confronted with persistent boot errors, resorting to advanced troubleshooting techniques may be necessary. One such set of tools is the Windows built-in command-line utility called Bootrec.

Bootrec provides a range of commands designed to diagnose and repair various types of boot-related issues on x86-64 systems running Microsoft operating systems including Windows 7/8/10 and Server versions thereof. In this article, we'll focus specifically on three commonly used boot related tasks performed using the following subcommands within BootRec:

1) /fixmbr

The fixmbr command is primarily employed when there are problems with either or both of these components which can lead to an inability for Windows to start up properly after a system failure such as hardware failure causing damage.

2) /rebuildbcd

This option attempts to rebuild the Boot Configuration Data (BCD) store located at C:\boot\Boot. This process involves scanning all available partitions on disk(s), identifying potential bootable ones, and then adding them into this configuration file so that upon next reboot only valid operating systems will appear during initial loading phase!

3) /fixboot

The fixboot command is used to repair the Master Boot Record (MBR)/Boot sector of a partition. This can be necessary when there are problems with either component leading an inability for Windows.

Here's how you might use these commands together:

1. Open Command Prompt or PowerShell as administrator.

2. Type 'bcdedit /set {default} bootstatuspolicy ignorebootifallfailed' and press Enter (this will ensure that even if all other boot options fail, the computer will still attempt to start from its current location).

3. Now execute one of these three commands depending upon your specific issue:

a) If you're experiencing issues with MBR/Boot sector: 'bcdedit /set {default} timeout 10' followed by pressing F2 during POST and selecting Troubleshoot -> Advanced options -> Command Prompt (or Shift + F8 on newer UEFI systems).

b) For problems related to BCD store itself:

a1. Press shift+Esc while booting into safe mode then type 'bcdedit /fixmbr' followed by pressing Enter.

a2. Reboot from USB stick containing repair tools and press Shift + F10 when prompted for advanced options.

4) After running the above commands, restart your computer normally to see if it boots up correctly without any further errors!

Troubleshooting Tips:

If you're still encountering access denied messages while attempting these steps, here are some additional troubleshooting suggestions:

- Ensure that Disk Management is enabled in Device Manager. You can do this by pressing Win + R together and typing 'msconfig' followed by navigating to the Boot tab.

- Check whether UEFI firmware settings allow booting from USB drives or SD cards - often found under Security > Secure Boot Configuration.

In conclusion, when faced with persistent boot errors that resist traditional troubleshooting methods, resorting to advanced tools like BootRec can be a lifesaver. Remember always to approach these kinds of changes cautiously and consider backing up important data before attempting any drastic measures!

Bootrec fixboot access denied reddit