Bootmgr is missing - what does this mean and how do you fix it?
The Windows Boot Manager (BOOTMG) is a tiny piece of software that's preloaded into Microsoft operating systems and is responsible for taking the computer through its initial startup stages and preparing it for use.
It's a critical component to Windows, as without it the OS will be unable to initialise automatically and you will be forced to manually boot the machine using its BIOS - namely by executing winload.exe, otherwise handled by the boot manager.
However, a missing boot manager is a common error - typically indicated by the "bootmgr is missing" message on a blue Windows screen. Although it can be alarming to have your PC suddenly refuse to boot, the fix is a fairly straightforward one, albeit a little time-consuming.
As the message suggests, the "bootmgr is missing" error indicates that the machine is unable to locate the manager and, therefore, can't run it. As mentioned, this is a fairly common error, particularly as it can be caused by a wide range of factors, whether that's something as innocuous as a failed Windows update, to something a little more serious, like a virus.
All you need to fix this issue is another computer and some spare time.
The first, perhaps rather obvious step to take if your machine is showing the "bootmgr is missing" message is to switch your computer off and then on again. Although it seems very simple, and is often joked about, it actually is sometimes the most effective remedy to an intermittent problem.
But if that still doesn't rectify the message, you should remove all externally connected devices, whether you have a USB key connected, a NAS drive or CD/DVD. Any of these could be feeding your machine with corrupt data that is preventing its normal startup. Try rebooting again.
If the computer still doesn't restart, it's time to get into the core of your machine and access your PC's BIOS settings. You can do this by pressing the F2, F12 or Del keys immediately powering it back up.
Now, take a careful look at the system's boot order and make sure it's set to start up from the first installed Windows drive.
Repairing the boot
If this doesn't fix the issue, you'll need to take more drastic action and attempt to manually repair the boot process yourself. The first step here is to set up your machine to boot from an external source - either the original Windows 10 startup disc or a USB.
This involves getting into your PC's BIOS settings, which can usually be done by pressing the F2 or Del key when the machine is first turned on. In the boot options choose a disc drive or USB to boot from, exit from BIOS settings and save changes.
Startup repair in Windows 10 and Windows 8
Startup Repair's role is to repair any files on Windows that may be missing or corrupt, making it a pretty powerful tool. Even something as vital to the core operating system such as Bootmgr can be fixed, as long as you have a Windows System installation media (a USB, CD or DVD with the disk image available for booting).
If you don't have a hard copy of Windows 10 or Windows 8, you'll need to create one before you start the process. You can do this by visiting the Microsoft download page and clicking on the link to download the MediaCreationTool.
Once you have the USB, CD or DVD created, restart your machine and when the "press any key to boot from CD or DVD" message appears, press Enter, then choose language, time and keyboard configuration. After clicking Next, choose the "repair your computer" option on the bottom left of the screen, choose Troubleshoot, Advanced options and Startup repair.
Once the computer has finished doing its thing, you can try and re-boot your Windows 10 or Windows 8 machine. If the computer starts up without the "bootmgr is missing" message, you have just fixed the issue! If not, you may have to seek professional help.
Startup repair in Windows 7
Repairing Windows 7 is broadly similar to repairing Windows 10 and Windows 8. In Windows 7, you will need to boot from the Windows 7 disc. You should wait for the setup process to load up files. Select the Language to install, Time and currency format, and Keyboard or input method that you'd like to use, then click Next. On the bottom-left of the Install Windows window, click on the "repair your computer" link.
This will start the Windows 7 System Recovery Options which features several suitable diagnostic and repair tools, one of which is Startup Repair.