WHAT IS WINDOWS BOOT MANAGER

A device running Windows 10 has several requirements for booting into the OS. After the device’s firmware initializes all the hardware, the device needs to ensure that there is enough power to boot. Afterwards, the device needs to ensure that the device is booting into the appropriate OS depending on if the user wants to perform an update or a restore on the device, or if the user wants to boot the device into the main OS.

To accommodate each of these scenarios, the Windows 10 boot process uses the following components:

• Firmware boot loaders provided by the System on Chip (SoC) vendor.
• UEFI (Unified Extensible Firmware Interface) environment provided by the SoC vendor.
• Windows Boot Manager provided by Microsoft.

The Windows Boot Manager is a Microsoft-provided UEFI application that sets up the boot environment. Inside the boot environment, individual boot applications started by the Boot Manager provide functionality for all customer-facing scenarios before the device boots.

The Windows Boot Manager is a piece of software that loads your computer’s operating system during the start-up process. Not only that, but it can also help you choose a specific operating system from a list of operating systems, if you’re using multiple operating systems. It’s one of the many handy tools at our disposal that makes our life easier in the Windows environment. In what follows, we’ll run through a brief introduction on Boot Manager. So let’s dive in.

Boot applications implement functionality for the following scenarios:

• Charging the device battery before boot.
• Capturing and saving offline crash dumps (developer builds only).
• Flashing the device with a new image.
• Resetting the device.
• Updating the device.
• Booting the device to the main OS.

The following diagram illustrates some of the key portions of the process that the Boot Manager follows after it is launched by the UEFI environment.

1. After the UEFI environment launches the Boot Manager, the Boot Manager initializes boot libraries, reads the boot configuration database to determine which boot applications to run and in which order to run them. The Boot Manager launches boot applications sequentially, and each application exits back to the Boot Manager after finishing.Boot libraries are libraries of functions that extend upon existing UEFI functionality, and are designed to be used within the boot environment. Only boot applications, which are launched by the Boot Manager, have access to the boot libraries.
2. The Boot Manager first captures any reserved hardware button combinations that are pressed by the user.
3. In non-retail OS images, the Boot Manager next runs an offline crash dump boot application which allows the device to capture a snapshot of physical memory from the previous OS session. When the device resets abnormally, the previous OS session’s memory is preserved across the reset. When this happens, the offline crash dump application will save that memory and turn it into an offline crash dump file, which can be transferred off the device and analyzed. If the device did not reset abnormally in the previous OS session, the offline crash dump application exits immediately.
4. In all OS images, the Boot Manager next runs mobilestartup.efi. This application runs several boot libraries, some of which are only run on first boot (for example, to provision the secure boot policy) or only in non-retail images (for example, to enter USB mass storage mode). The following libraries are always run:
   1. First, mobilestartup.efi runs the library that implements UEFI battery charging. This library allows the user to charge their device while the device is in the boot environment (or is perceived as being turned off). This library is run first to ensure that the device has enough power to fully boot. For more information about scenarios involving the battery charging application,

What does the Windows Boot Manager do?The Windows Boot Manager is a Microsoft-provided UEFI application that sets up the boot environment. Inside the boot environment, individual boot applications started by the Boot Manager provide functionality for all customer-facing scenarios before the device boots.

How to Enable/Disable Windows 10 Boot Manager

Based on the above description, you can know that Windows boot manager Windows 10 is beneficial to your computer. Additionally, if you have multiple operating systems, you can choose the target operating system and enable Windows Manager when booting your computer.

However, as it can unnecessarily slow down the boot process when it waits to ask you which operating system to boot to, you may want to disable it.Tip: If you don’t want to choose which operating system to boot to and always like to start the same one, you can pre-select the one you always want to start.

Actually, you are unable to delete Windows boot manager. What you can do is to reduce the time that it waits on the screen for your answer which operating system you would like to start. You can utilize the given methods to enable/disable Windows 10 boot manager.Tip: You should be careful when using system configuration data. Don’t do some unnecessary changes. That will lead to more mess.

Method 1: Utilize Command Prompt

To enable/disable BOOTMGR via Command Prompt, you need to have administrator privilege to perform. If you don’t have this access, it is suggested that you use  Renee PassNow to create one before following the steps below.

Step 1: Type cmd in the search box, and then right click Command Prompt and choose Run as administrator.

Step 2: Type the following commands in the Prompt and hit the Enter key after typing each one command.

• bcdedit / set {bootmgr} displaybootmenu yes
• bcdedit / set {bootmgr} timeout 30

Tip: The timeout decides the time of boot manager displayed. You are able to specify the timeout value in seconds based on your requirement.

Step 3: If you want to disable Windows Boot Manager, you need to type bcdedit / set {bootmgr} timeout 0 and hit Enter.

You can also use the bcdedit / set {bootmgr} displaybootmenu no command to disable BOOTMGR, but by doing so you cannot use the Method 2.

Method 2: Change System Properties

Alternatively, you can change System properties to enable or disable Windows Boot Manager. Here are steps for you.

Step 1: Open the Run dialog window by pressing Win plus R keys.

Step 2: Type sysdm.cpl and click OK to continue.

Step 3: When the System Properties window pops up, choose the Advanced option. Then click on the Settings under the Startup and Recovery option.

Step 4: In the pop-up window, select the Time to display list of operating systems box and set the time value. After that, click OK to save the changes.

Step 5: If you want to disable BOOTMGR, cancel Time to display list of operating systems box or set the time value as 0 and click OK to finish the operation.

Extra Information about BootMGR

The common boot error in Windows is the BOOTMGR is missing error. The Boot Configuration Data store is safer than the boot options in previous. That is because it enables users who are in Administrator group to lock the BCD store partition and gives some rights to other users to decide which ones can manage boot options.

Only if you are in the Administrators group, you can edit the boot options in Windows Vista and more advanced Windows versions utilizing BCDEdit.exe tool included in those versions of Windows. On the contrary, if you’re using older versions of Windows, use the Bootcfg and NvrBoot tools instead.

HOW TO FIX WINDOWS BOOT MANAGER PROBLEM

1. Press F8 while booting the system to go into the Windows Recovery Menu.
2. Click on Troubleshoot.
3. Click on Advanced options to get into Automatic Repair menu.
4. We need to use the Bootrec.exe tool. Click on command prompt and type in the following commands, one after the other:
   bootrec /RebuildBcd
   bootrec /fixMbr
   bootrec /fixboot
   bootsect /nt60 SYS or bootsect /nt60 ALL
5. Exit and now go ahead and reboot your system.

We highly recommend that you backup your Master Boot Record or create a System Recovery Disk so that in case something like this happens you don’t have to run the Windows Recovery Disk. To create a system recovery drive, just follow the steps listed below:

1. Press the Start button.
2. Type RecoveryDrive.exe.
3. Click Next
4. Once you insert the USB drive, it will start creating the Recovery on your USB drive.

Fixing “BOOTMGR is corrupt” on Windows

Windows Setup CD/DVD Required!
Some of the solutions below require the use of the Microsoft Windows setup CD or DVD. If your PC did not come with a Windows installation disc or if you no longer have your Windows setup media, you can use easy recovery essential for windows instead. EasyRE will automatically find and fix many problems, and can also be used to solve this problem with the directions below.

Fix #1: Rebuild BOOTMGR via Easy Recovery Essentials

Easy Recovery Essentials’ one-click automated system repair corrects issues caused by corrupt BOOTMGR bootloader files by recreating them from scratch on the active bootable partition. This is done automatically as part of the automated repair process, and requires no manual action or user intervention.
 Easy Recovery Essentials is guaranteed to fix the “Bootmgr is corrupt” error automatically using its built-in Automated Repair option. EasyRE is currently available for Windows XP, Vista, 7 and 8 and can be downloaded and created on any PC.

1. Download Easy Recovery Essentials. Make sure to note your Windows version (XP, Vista, 7 or 8) before you download EasyRE.
2. Burn the image. USB stick drive
3. Boot up your PC or USB you created.
4. Once EasyRE is running, choose the “Automated Repair” option and click Continue.Choose “Automated Repair” in Easy Recovery Essentials
5. After EasyRE scans your computer’s drives, identify and select the drive letter for your Windows installation from the list, and then click on the Automated Repair button to begin.Choose the drive associated with the Windows installation you’re trying to repair.
6. Easy Recovery Essentials will start analyzing the selected drive for problems. EasyRE will test for and attempt to automatically correct errors with the disk, partition, bootsector, filesystem, bootloader, and registry. No intervention is required, as EasyRE’s repair is fully automated:Easy Recovery Essentials searches for errors and makes corrections to the selected Windows installation.
7. Once the process is complete, EasyRE will report its findings. Click on the Restart button to reboot your PC and test the changes.
8. The “Bootmgr is corrupt” error should now be fixed as your PC begins to load:Windows, booting up successfully.

You can download Easy Recovery Essentials from here.

Fix #2: Use Startup Repair to repair BOOTMGR

On Windows Vista, Windows 7, Windows 8, Windows 8.1 and Windows 10, Startup Repair can be used to scan the system for damaged or missing system files to replace the BOOTMGR file if it is corrupt or missing.

Windows Setup CD/DVD Required!
Some of the solutions below require the use of the Microsoft Windows setup CD or DVD. If your PC did not come with a Windows installation disc or if you no longer have your Windows setup media, you can use easy recovery essential for windows instead. EasyRE will automatically find and fix many problems, and can also be used to solve this problem with the directions below.

Startup Repair is an automated diagnosis and repair tool that is available from the Windows setup disc and can be used to find and repair some common problems. More information about how Startup Repair operates and what it does can be found in our knowledgebase. The following steps will initiate Startup Repair from the Windows setup disc:

Unable to boot into the Windows setup CD?.

1. Insert your Windows installation DVD into your PC’s CD-ROM drive,
2. Fully power down your PC, and make sure it has fully shut off,
3. Power up your PC,
4. Press any key when you see “Press any key to boot from CD or DVD..”
5. Click the link titled “Repair your computer” in the bottom-lefthand corner, after first selecting your language and keyboard options.
   
6. Wait for Startup Repair to scan your PC for Windows installations, then select your install from the list it shows:
   
7. Choose “Startup Repair” from the list of available recovery options to begin:
   
8. Startup Repair will begin scanning your installation for known issues and will attempt a repair, if possible.
   

Here is an example of what the PC’s startup repair should look like once the BOOTMGR file is properly restored:

Corrupt bootmgr fixed by Startup Repair

Fix #3: Update BOOTMGR manually

Since the boot error is often caused by a corrupt BOOTMGR, replacing it with the correct version is often a good and effective solution.

Here are the steps to replace the BOOTMGR:

1. Boot from the Windows install disc
2. Click on Repair your computer after selecting proper language, time and keyboard input.
3. Select the Windows installation drive, which is usually C:\, and click Next
4. Choose “Command Prompt” when the System Recovery Options box appears
5. Type in the following command and then press Enter:bcdboot C:\Windows /s D:\Where C:\Windows is a Windows installation folder and D:\ is an active boot partition.

Here is an example screenshot of what the PC’s console output should look like after the BOOTMGR is updated correctly:

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