2. Resolving Boot Errors: Fixing Corrupted Boot Manager or Missing Boot Entries
Corruption in the Boot Manager or loss of boot entries can result in Windows not booting. Some common mistakes that can be fixed by editing BCD include:
- “Bootmgr is missing”
- “Operating system not found”
- “The boot configuration data file is missing or contains errors”
One of the most commonly used solutions to solve this problem is to run the following command in Command Prompt in Recovery mode:
bootrec /rebuildbcdThis command will search for an existing operating system and add it back to the BCD.
3. Boot Optimization: Setting a Waiting Time or Changing the Boot Order
Windows gives a waiting time before choosing the default operating system on a computer that has more than one OS. If the user wants to reduce the waiting time or change the boot order, the BCD can be adjusted to speed up the boot process.
Setting the boot timeout (in seconds):
bcdedit /timeout 5Change the boot order to make Windows 11 default:
bcdedit /default {current}4. Windows Boot Customization: Specifying the Default OS, Enabling Debugging, and More
More experienced users may want to enable debugging options, safe mode, or run certain commands at boot. Using BCD, users can perform some additional settings such as:
Enable debugging for system analysis:
bcdedit /debug ONRunning Windows in safe mode:
bcdedit /set {current} safeboot minimalHow to Access and Edit BCDs with BCDEdit
Step 1: Open Command Line as Administrator
To start editing the BCD, you need to open the Command Prompt or Windows Terminal as an Administrator. How:
1. Right-click on Start Menu.
2. Select Command Prompt (Admin) or Windows Terminal (Admin).
Step 2: Use BCDEdit Commands
Once the Command Prompt opens, type the following command to view the contents of the BCD:
BCDEditStep 3: Understanding BCD Identification
Each entry in the BCD has an Identifier that can be a technical name, a text string, or a GUID (General Unique Identifier). Example:
{current}This identifier is used to refer to the main operating system that is running.
BCDEdit Command List and Its Functions
BCDEdit is a built-in Windows tool that is used to view and manage Boot Configuration Database (BCD). With this command, users can edit boot entries, adjust operating system settings, and fix boot issues. Here is a list of basic BCDEdit commands and their functions.
BCDEdit Basic Commands and Their Functions
| BCDEdit Commands | Function |
| bcdedit /enum | Displays a list of all entries in Boot Configuration Database. |
| bcdedit /copy {id} /d “OS Name” | Make a copy of an existing boot entry with a new description. |
| bcdedit /delete {id} | Removes unnecessary boot entries. |
| bcdedit /set {id} option value | Changing the boot parameters for a specific entry, e.g. enabling safe mode. |
| bcdedit /default {id} | Set the default operating system to run at boot. |
| bcdedit /timeout X | Specifies the timeout before selecting the default OS (in seconds). |
| bcdedit /bootsequence {id} /addfirst | Set the boot order for one subsequent boot. |
| bcdedit /export filename | Making backup BCD for future recovery. |
| bcdedit /import filename | Import a previously saved BCD backup file. |
| bcdedit /rebuildbcd | It scans all available operating systems and fixes missing boot entries. |
Table of Identifiers in BCDEdit
Each entry in the Boot Configuration Database has a unique identifier used in the BCDEdit command. Here are some identifiers that are often used:
| Identifier | Function |
| {current} | The operating system that is currently in use. |
| {default} | The default operating system is automatically selected at boot. |
| {bootmgr} | Windows Boot Manager that manages the boot process. |
| {ntldr} | Loader for older versions of Windows (XP and earlier). |
| {memdiag} | Windows memory diagnostic tool. |