Do not panic if you encounter this error while loading the operating system (OS). It is relatively easy to fix. It is enough to understand the reasons, and then act correctly.
Causes of errors
BOOTMGR is a bootloader for Windows OS starting from Vista. It loads the Windows kernel into the operating memory, prepares the equipment for work, determines which operating systems are installed on the computer. That is, he is responsible for starting the system, so if it fails, it is impossible to use the computer. The insidiousness of the problem lies in the fact that the OS will not boot in either normal or safe mode. This error may also precede the imminent failure of the drive.
BOOTMGR is compressed
Means that the file has been compressed, and therefore cannot be normally detected by the BIOS-UEFI firmware of the motherboard, which starts before Windows starts. In the vast majority of cases, such a failure is caused by the activated option to compress the system disk to save free space. That is, a special utility took and archived BOOTMGR, but in this form it cannot function normally. Also, in some situations, an error may mean that the file has become corrupted.
BOOTMGR is missing
Indicates that the file cannot be found on the hard disk. This does not necessarily mean that it has been erased or moved. For such manipulations, you still need special permission and good knowledge of computers. Sometimes a failure occurs due to the wrong boot priority – the BIOS chooses the wrong drive to start the OS.
BOOTMGR is is corrupt
Indicates that the file is corrupted and cannot be fully read from disk. The rarest version of an error, but its consequences are the most sad. This most often occurs when the surface of the magnetic platters on the hard disk drive (HDD) is significantly degraded or when the resource of data write cycles to a memory cell in a solid-state disk (SSD) is exhausted.
How to fix it
Generalized To troubleshoot BOOTMGR is compressed, do one of the following:
- eliminate the factor causing the bootloader to fail;
- repair or replace the bootloader.
Method 1. The problem appeared due to incorrect options in the BIOS.
This is typical for computers with multiple attached storage devices. For example, an SSD might have an OS, and an HDD might have basic user files. The BIOS may turn off the boot priority option and then it should be returned to its original value.
Change BIOS settings
To do this, do the following:
- Go to BIOS. To do this, before the error occurs, press Del, F2, F12, F10 or another button that will be indicated on the screen to start the BIOS. Take your time, the notification about the required key will definitely appear, you just need to be careful, there are not so many lines to miss.
- Go to the “Boot” tab. It can be named differently depending on the motherboard firmware version. Look for the lines “Boot Devices Priority” and “Hard Disc Drives” on this tab. Again, the names may differ in your case, but not significantly.
- Make sure that in the “Hard Disc Drives” settings, the drive on which the OS is installed is in the first place. In “Boot Devices Priority” make sure that the information is loaded from the hard disk first, not the optical drive. Correct settings should be everywhere, otherwise change them.
- Save your changes. This can be done by pressing F10 and confirming the operation Yes (Y, OK). Perhaps in your BIOS you just need to go to the “Save Changes & Exit” option.
After these manipulations, BIOS-UEFI will look for the OS bootloader on a suitable drive.
Factory reset
There are two ways to act:
- Take out the CMOS memory battery. Suitable for desktops that can be disassembled. Remove the side cover, find the coin-cell battery on the motherboard and pull it out for 10-15 seconds. After that, all settings will be restarted to the standard ones.
- Reset settings programmatically. To do this, go to the BIOS and activate the “Load Defaults BIOS” option (“Load BIOS Setup Defaults”, “Load Safe-Fail Defaults”).
Method 2. The problem appeared due to a software failure
BOOTMGR is compressed is displayed on a black background, what should I do? In most cases, the problem is in the system file, which for unknown reasons has lost its original form.
System rollback
The easiest way is to use the built-in OS tools to replace the faulty file with a normal one. This will require an installation disc or flash drive.
Preparing a disk or flash drive with Windows installation files
It is required to capture an image of the version of Windows that is currently installed on the computer. There is no fundamental difference between an optical disc or a USB stick. In each case, it is only important to correctly set the appropriate boot priority in BIOS-UEFI. The recording procedure itself follows the standard scheme, as a result, you should have a bootable media on hand from which you can install Windows.
Installation for Windows 7
Follow these steps:
- On the initial OS installation window in the lower left corner, click on “System Restore”.
- The “Windows Recovery Options” window will appear, in which you click on the OS that does not want to boot on your computer.
- In the next window, first click on “Startup Recovery”. After that, the verification procedure will begin, which can take quite a long time. If at the end of the crash, then return again to this window and click below on the line “Command line”.
- In the resulting black window, copy the bootrec / fixmbr command and run it by pressing Enter. Next, do the same with bootrec / fixboot.
- Close the recovery utility, reboot the system, re-install the first boot from the drive where Windows is installed. The error should go away as you created a new normal BOOTMGR file and told the OS that it should boot with it.
Installation for Windows 8 and 8.1
Proceed according to the following algorithm:
- On the initial OS installation window, follow the path: “System Restore” => “Windows 8” => “Diagnostics” => “Advanced Settings” => “Automatic Recovery”.
- First click on “System Restore”. After that, the verification procedure will begin, which can take quite a long time. If at its end the failure appears again, then return to this window and click on “Command Prompt”.
- In the resulting black window, copy the bootrec.exe / FixMbr command and run it by pressing Enter. Next, do the same with bootrec.exe / FixBoot. Then close the window and restart your computer. If the problem persists, then return again to this window.
- Run the bootrec.exe / RebuildBcd command. It will scan all drives for the presence of an OS, and when it finds one, it will ask you that the OS will be included in the boot list. You need to confirm this manipulation by entering Y and pressing the Enter button.
Installation for Windows 10
Follow the same steps as in the previous block, but run another command in the Command Prompt – bcdboot X: Windows / s Y: , where:
- X: Windows – the folder with Windows on the disk, in your case, most likely, it will be C: Windows;
- Y – designation of the flash drive or optical disk from which the system is being restored;
- to find out exactly the drive letters, enter the diskpart and list volume commands.
This will replace the damaged BOOTMGR bootloader with a normal one, which will be copied from a bootable USB stick or disk.
Method 3. Solving the problem using programs
An error with the bootloader implies a complete impossibility of starting the OS, so it is definitely necessary and can only be booted from a USB flash drive or LiveCD. After that, you will gain access to the main drive and the question will be in choosing the appropriate utility for restoring BOOTMGR. There are many of them, but consider MbrFix. For one hard disk in a system with one local disk on which the seventh version of Windows is installed, you only need to run the command MbrFix.exe / drive 0 fixmbr / win7. For other operating systems and configurations, you should refer to the detailed instructions, they are easy to find on the net.
How to prevent future mistakes
To avoid errors, follow these steps:
- Disable data compression on the local drive where Windows is located. To do this, go to “My (This) Computer”, right-click on the first disk => “Properties” => “General”. Uncheck the “Shrink this disc” line.
- Monitor the status of your drive. If you have an SSD, then use the manufacturer’s monitoring utility, it is available for any well-known brand. If you have an HDD, then monitor the SMART parameters.There are many applications for this, among the free we recommend CrystalDiskInfo.
Conclusion
- The failure was caused by the inability to start the OS bootloader.
- To eliminate it, the easiest way is to use the Windows recovery tools.
- Sometimes the problem only portends a serious breakdown of the drive.