Checking for the presence of an EFI application
Having decided on a partition that can act as a boot one, you need to check for the presence of the corresponding boot files on it. From the previous section, we found out that this can be a partition mounted under the FS0 label.
For the sake of convenience, hereinafter in the text, I will refer to mount point marks as disks. SIMilar to disks in Windows operating system, followed by a colon. UEFI Shell in this regard, just copies, in its habits to a greater extent, the Windows CMD command shell.
Let’s go to disk FS0.
The command prompt will change to reflect your current location on the file system. At the moment, this is the root of the FS0 drive. View its contents.
At the root of the disk, only the directory is present EFI. Let’s go to this directory and see what is in it.
Inside the directory EFI there are three subdirectories Boot, Microsoft and ubuntu. Catalog Boot is in this case bootable by default. It contains boot.Efi boot applications, which are launched by the UEFI subsystem automatically. Browse the contents of a given directory.
The command output shows that in the directory Boot contains three files, one of which is bootx64.Efi. This file is launched automatically by the UEFI subsystem. I want to draw your attention to the colors of these files, in the output of the ls command, they are green. This means that these files are executable and can be started manually.
If you run the bootx64.Efi file now, the GRUB2 boot loader will boot.
Catalogs Microsoft and ubuntu, contain the bootloader files for Windows Boot Manager and GRUB2 respectively.
For catalog Microsoft, main loader files are located in a subdirectory Boot.
The main bootloader at the moment is GRUB2. This means that the file /EFI/Boot/bootx64.Efi how does it use the contents of the directory / EFI / ubuntu /. Whether it’s running an executable or reading a config file. Let’s take a closer look at the contents of the folders / EFI / Boot / and / EFI / ubuntu /.
Pay attention to the files shimx64.Efi and bootx64.Efi, or rather, their size. I guess you guessed that these files are identical. This means that there is no point in running a copy of the bootx64.Efi file. There are two options left, either it is the grubx64.Efi file, which is more obvious from the file name, or mmx64.Efi. Run the mmx64.Efi file to make sure that this is the wrong application.
Expectations were confirmed, the GRUB2 bootloader was clearly not opened.
Let’s summarize the intermediate result. File /EFI/Boot/bootx64.Efi is actually a file /EFI/ubuntu/shimx64.Efi. application /EFI/Boot/bootx64.Efi on startup, calls another application, namely /EFI/ubuntu/grubx64.Efi. You can verify the latter by SIMply renaming the file /EFI/ubuntu/grubx64.Efi, followed by an attempt to boot from this disk.
What can be useful from this information? The most important thing is that the folder / EFI / ubuntu / contains a complete set of files. If suddenly, for some reason, the original file /EFI/Boot/bootx64.Efi will be deleted or damaged, then it can be easily restored by SIMply copying the file /EFI/ubuntu/shimx64.Efi followed by renaming to bootx64.Efi.
This behavior is typical for the directory / EFI / Microsoft / Boot /. It also contains everything you need. File role /EFI/Boot/bootx64.Efi will perform /EFI/Microsoft/Boot/bootmgfw.Efi. Which in turn will run the file /EFI/Microsoft/Boot/bootmgr.Efi. That is, by performing such a substitution, the Windows Boot Manager will start instead of the GRUB2 boot loader. Let’s try to make such a substitution.
Windows Boot Manager successfully launched and loaded the Windows 10 operating system.
To put the GRUB2 boot loader back in place, SIMply delete (or rename) the current file /EFI/Boot/bootx64.Efi, and rename /EFI/Boot/bootx64.Efi_ to its former name bootx64.Efi.
All subsequent operations will be performed on the VirtualBox virtual machine. On a virtual disk, two operating systems are installed, Windows 10 and Ubuntu 18.10. GRUB2 is used as the main bootloader. Windows Boot Manager bootloader, also present, but not used.
It will NOT be superfluous before you start working with the UEFI Shell, Read the description of this command shell available at this link https://www.Bootdev.ru/2018/05/EFI-Shell.html.
Create bootable disks and other useful little things
Outputting Boot Records
Any boot problem should start by analyzing boot records. List current records.
The current boot configuration has three entries.
Entry 0. Booting from floppy drive.
Entry 1. Booting from hard drive.
Entry 2. Loading the built-in UEFI Shell.
Of the entries present, only one can boot the operating system, this is entry number 1 (in fact, the second). Remember the disk number and its type from the DevPath parameter.
If there are problems with loading the operating system, then you need to check whether the specified disk is present, and the presence of an EFI section and an EFI application on it.
Booting into UEFI occurs according to boot records. If in the BIOS, these entries were just a list of available hard drives, then UEFI in this regard operates according to a different scheme. By default, UEFI detects all disks with MBR and GPT partition tables, and then searches them for partitions formatted in a supported file system. This is FAT (12, 16, 32). These disks are included in the boot list. The boot priority of this list can be configured through the UEFI interface, or using the UEFI Shell.
Each boot record can point either SIMply to the disk that contains the Corresponding FAT partition, or to a specific.Efi file. In the first case, UEFI will look for the default boot file. Such, for example, are /EFI/boot/bootx64.Efi, /EFI/boot/bootia32.Efi, /EFI/boot/bootarm.Efi or /EFI/boot/bootaa64.Efi. In this case, the boot.Efi files are specified for different PC architectures.
The boot.Efi executables run the main operating system boot loader such as Windows Boot Manager, GRUB2, rEFInd, Clover, Xorboot and others. The loader, in turn, is already starting the operating system kernel.
Considering all of the above, we can draw a conclusion. Since the UEFI Shell flaunts in front of us, it means that the UEFI subsystem, for some reason, could not find the necessary bootable.Efi file. It may be damaged or SIMply missing. Or, as mentioned a little above, the priority of the boot records may SIMply be changed. And the last option, the required boot record is SIMply missing.
UEFI Shell. It is a manual download management tool. If you did NOT initiate the launch of this command shell, then this means that you need to check the boot configuration. And it is not necessary to do this precisely because of the team term. First, we understand the configuration in the UEFI menu. And if there are results, then go to the next section.
What to do in UEFI Shell
Once in the UEFI Shell, the first thing you need to do is, surprisingly, adjust the console colors and size. This is done in order to get rid of unreadable blue text on a black background. Resizing the console will allow more information to be displayed. The cls and mode commands will help you to tweak the look.
After customizing the appearance, you will need to view information about the boot records. This information will allow you to determine which bootable EFI applications should be loaded, in what order, and on which partitions they should be located. Bcfg command.
The last step is to manually check the ability to boot from a specified EFI application or disk.
An important nuance of this step is that the required EFI application can be present. But there may be no application that is launched by this application. Or it may be damaged.
For example, the application /EFI/Boot/bootx64.Efi, Specified in the boot record, runs /EFI/Microsoft/Boot/bootmgfw.Efi, which launches an application that starts the operating system from a different partition /Windows/System32/Boot/winload.Efi.
If the boot record points directly to the disk, then when booting from such a record, the drive will search for the bootable EFI partition, and if it is found, the default EFI boot application (/efi/boot/boot.Efi).
For such an entry, you need to check for the presence of an EFI partition on the disk, and an EFI application located in the / EFI / boot / folder. The map commands will help with this. Cd and dir.
Configuring the Console
Let’s set the parameters of the background color and text of the UEFI Shell. In my opinion, colors are optimal for readability. Gray for background and black for text.
The available color options can be found in the command help.
The console size is set with the mode command. First, we enter this command without any arguments to determine the available console permissions.
And after that, indicating the required permission.
Default Boot Device Missing or Boot Failed. what to do with an error
When attempting to boot the laptop, a “Default Boot Device Missing or Boot Failed” message appears. Most often, this error can occur after an emergency shutdown of the PC. Our small overview of solutions will allow you to quickly deal with the problem and restore the machine to work.
Failed to boot “Default Boot Device Missing or Boot Failed”
Basically, this error pops up in Lenovo and Acer models and indicates that the boot settings have fallen off. First of all, check if the BIOS is set to boot from HDD by default. This is checked in the “Boot Device Priority” option. It is possible that the first time you do not start up in the BIOS, try to enter several times. The best solution is to remove the battery on the board for a reset. it’s such a small coin cell. In the second cases, the reason lies in the use of the basic UEFI system instead of the standard one in the BIOS. We need to switch.
- Restart your computer.
- After turning it on, press the “F2” button.
- Getting into BIOS.
- We go to the last tab “Boot”
- The first term “Boot Mode” switches to “Legacy”, and “Boot Priority” to “LegacyFirst”.
- Next, go to the Exit tab, where I confirm the “Load Default Settings” mode from “Yes”.
- We exit BIOS, saving changes in “Exit Saving Changes”.
If everything is done correctly, it should start. If there is still a launch, then try to insert the WIndows installation image, register the boot from the media and enter the Win startup recovery mode there.
What to do if BIOS does not start?
If the BIOS does NOT boot at all, then you should use third-party software. The Rufus utility will help us here. This application will allow you to restore boot files so that we can make a normal start of the operating system on a laptop with a malfunction. You need to download Rufus to a third-party computer, stock up on a USB flash drive and download BIOS for your model.
The procedure is as follows.
- Will launch Rufus.
- Insert USB stick. The memory card must be formatted in FAT format
- We press “Start”. At this time, the flash drive is formatted according to the standard we need. In fact, we make it bootable. It remains to fill it with content.
- Now we turn to the downloaded BIOS. Before us is the archive. You need to unzip its contents to any directory.
- We open this folder. Copy the contents to a USB flash drive, but the files there DO NOT delete!
- Removing the USB flash drive and inserting it into our laptop.
A separate point is flashing your BIOS in Crisis Recovery Mode. This process is quite difficult and the serial number can fly off, which is associated with a guarantee, it is better to let specialists do this.
The problem of Default Boot Device Missing or Boot Failed is solved only in BIOS, I hope you understand what to do there. Once fixed, It will not prevent the operating system from loading. Finally, a little. For the correct boot setup:
Influence of the secondary periphery
Connected third-party peripherals often disrupt the boot order in the BIOS. If you do not find the desired bootable device, the computer will display the message. no bootable device.
Therefore, the first and SIMplest thing to do is to turn off all secondary peripherals. It includes various peripherals connected via USB: flash drives, scanners, printers, Wi-Fi, Bluetooth modules, and more. Then check the result.
If the problem is solved, then in order not to turn off all the equipment every time, you just need to change some settings in the BIOS, how to do this, I will tell you below.
Couldn’t fix the problem? Seek help from a specialist!
Defects on the side of other components
It is possible that the prerequisite for the emergence of no bootable device hit any key was the motherboard or power supply.
Motherboard. SATA connector may be defective or swollen capacitors on the motherboard side.
To check the first moment, it is enough to connect to the second connector.
The second point is determined by eye, Inspect the capacitors, make sure they are of a standard shape and NOT swollen. Otherwise, they should be replaced.
Power Supply. If it is not under warranty, then we will disassemble it and make sure that the capacitors and the board itself are intact. If the warranty is valid, then it is better to take it to the service center for diagnostics.
But again, the faulty power supply will say a sharp shutdown of the computer or turn on NOT the first time.
It happens that its capacity is not enough and it cannot provide all the components with stable operation. To check this, disconnect all secondary peripherals and accessories from the PC.
Checking the connection of the hard drive
Quite often, the no bootable device error, most often with the text “is detected” or “found”, appears as a result of an incorrectly connected drive. Therefore, first of all, you need to make sure that the hard drive is connected correctly.
To do this, let’s disassemble our laptop or, in the case of a computer, just open the side cover of the case. The PC itself must be turned off.
Disconnect the SATA cables and reconnect them to the hard drive. They must fit snugly against their connectors.
Most often this will fix the problem.
Broken USB connector
Quite often, users try to find the root of the problem, when it can be found in the SIMplest and most obvious places. Which include a non-working USB connector.
To check this, try connecting the USB flash drive to the second connector, preferably on the back panel. Also, the operation of the connector can be checked by connecting any other USB device.
Also, the error could appear due to additional devices connected to the computer. Seeing them, BIOS changes the boot queue as it sees fit.
Let’s assume that Windows is installed on the hard drive, and the PC is looking for it on the connected USB flash drive. If you do not find it, it will display the corresponding message. no bootable device.
To get rid of it and get your computer working properly, you need:
- Go to BIOS settings.
- Go to the section responsible for the download queue. He usually calls it “Boot”, “Boot” or “BIOS Features”. In older BIOS versions, the necessary settings are located in the “Advanced Options” or “Advanced Features” sections.
- Find the parameter responsible for the startup priority. It may be named “1st Boot Device” or “Boot Option”. It all depends on the version.
- As the first device, set the hard drive with the installed Windows OS.
- Save settings and restart your PC.
This will most likely help solve the problem.
Sometimes it happens that the hard drive is NOT displayed in the BIOS, most often this is corrected by reconnecting, replacing the cable and diagnostics. I spoke about this above. In rare cases, the case may be a malfunction of the HDD, while various strange sounds appear (squeaks, clicks, knocks, etc.). Then only replacement will save.
What else can you do
If none of the above helped, then most likely the problem is of a technical nature, only experienced craftsmen can diagnose and fix it.
However, you can still try performing a clean install of Windows or flashing the BIOS if you have the necessary programmer.
It should be remembered that the text of the message, depending on the BIOS, is different, for example, in the last article I told you how to eliminate a SIMilar error “reboot and select proper boot device”. Some methods and recommendations from there may come in handy.
Another common cause of a no bootable device is a failed file system, boot record and other important Windows files. At the same time, it is not a fact that after their recovery, the performance of the computer will be fully restored.
I recommend that you first check the hard drive using Special programs, make sure it is working and only after that do the rest of the rest.
It does NOT hurt to additionally inspect the hard drive board for oxidation and physical damage, always on both sides. To do this, carefully remove it by unscrewing all the screws.
If there are oxides, the board should be cleaned with alcohol, acetone or gasoline “galosh” using a toothbrush. After cleaning, dry it thoroughly and screw it back to the drive.
When the laptop starts up, the POST check starts. If the hard drive is NOT stable and the BIOS does not see it, the corresponding message “No device is detected” will be displayed on the screen. The message text depends on the BIOS version.
This means that the previous methods did not bring the desired result, which in turn indicates a problem on the side of the hard drive mechanism. Only a complete replacement of the HDD will help.
But there is another option to check if the BIOS sees the hard drive. In it read below.
Recovering MBR and file system
Also, the no bootable device insert boot disk and press any key error may indicate a corrupted “MBR” boot record. In this case, it needs to be restored.
Detailed instructions using the example of Windows 7:
- First of all, you need to install a bootable disk or USB flash drive into the device.
- Go to BIOS and change the startup sequence by putting the floppy drive or USB flash drive in the first place.
- Select “Recovery.”.
- Mark the required Windows OS.
- Click the command line.
- Then, one by one, execute three commands, the first: enter bootrec / fixmbr and press “Enter”.
- After it we execute: bootrec / fixboot, pressed “Enter”.
- And the latter will allow you to check the file system: chkdsk C: / F / R. If Windows is installed on a different partition, then replace the letter “C” with the letter of your partition.
Everything should work now.
Replacing the SATA cable
Perhaps the old SATA cable (from the motherboard to the hard drive) is damaged, so it should be replaced.
Couldn’t fix the problem? Seek help from a specialist!
Examine the power cable that connects from the power supply to the hard drive. It and its contacts must be intact and tightly connected to the connector. Connect another cable if necessary.
In some cases, all the power cables may be damaged, then the installation of Special adapters helps, which can be purchased on the same Aliexpress.
Blinking white dash (cursor) when booting a computer or laptop. reasons and what to do
One of the common problems for users when booting a computer or laptop. both from the built-in HDD or SSD, and from a flash drive. is a black screen on which a white dash is blinking, or rather, an underscore character and no further loading occurs.
In this manual, in detail about what may be causing the problem and how to fix the situation if you encounter a white blinking dash when the computer boots.
White dashes on black screen when booting Windows 10
If the system is already installed on an HDD or SSD and during boot you saw a black screen with a blinking white cursor (or you see it sometimes when you turn it on, but next time the boot goes fine), a prerequisite may be problems with the bootloader, BIOS settings. as well as some of the features of Windows 10 related to the Connected Standby mode (the first point is just about this).
Try the following solutions in this situation:
- If the problem appears when you turn on your computer or laptop for the first time, but disappears itself when you turn it off and then turn it on, then when Windows 10 boots normally again, Disable the “Quick Start” function.
- Try to turn off the computer or laptop by long holding the power button, then disconnect any USB drives and memory cards (and other devices, if recently connected), turn the computer back on.
- If the problem appeared immediately after installing Windows 10 in the BIOS (UEFI) of your computer, instead of booting from the HDD or SSD, select “Windows Boot Manager” as the first item (if there is such an item).
- If the problem appeared after disconnecting one of the disks, the prerequisite may be that the system loader was on it (the system and the boot loader may be on different disks).
- If you reset the BIOS (or suspect that it reset itself), make sure you have the correct boot options. For example, for a system installed on an MBR disk, Legacy (CSM, Compatibility Support Mode) boot must be enabled and Secure Boot disabled, and for GPT disks, disabling Legacy mode support can help.
- If none of the options work, there is only one disk on the computer and previously booting from it was successful, you can try to restore the Windows 10 bootloader, but before that, in the same command line (how to open it is described in the instructions for restoring the bootloader) checking disk for errors using chkdsk.
Blinking white cursor when booting from a flash drive
The second most frequent case is a blinking “white dash” when booting a computer or laptop flash drive. Here the reasons are usually the same: the boot mode in the BIOS does NOT correspond to the mode for which the flash drive was prepared, in some cases. the Secure Boot option is enabled when booting from the drive, for which it should be disabled.
Details about all THESE points in a separate article A computer or laptop does not see the bootable USB flash drive in the Boot Menu. the context of the instruction is different, but all the described actions are also suitable for solving the problem in question.
The download manager has the following errors.
Disabling the boot manager
You can disable Windows Boot Manager in the BIOS. Directly instead of initializing the selected system, another will be initialized from the specified location. Another startup queue is set in the “Boot Priority” BIOS.
Bootmgr is compressed
An error occurred while starting the component. This event can be the result of damage to the Hard Drive or bootmgr itself. The fix is complex, but still available even to an ordinary user.
You will need to find the installation disk Windows will start the OS installation and go to the point of choosing the installation location. Instead of splitting the hard drive, go back one step and start the command timeline. The following command is entered into it: bootrec.Exe / fixmbr. This will write the default view of the boot manager and Windows can start normally. This measure is extreme!
The method also fixes the problem. Bootmgr is missing.
Physically Windows Boot Manager is located on the Hard Drive. But you will NOT be able to navigate to it through the explorer (unless the setting is done specifically for this). The physical location of the manager is tied to hide the system partition on the disk. “Reserved by the system”.
It should be noted that there are only 2 types of boot loaders for the Windows operating system: NTLDR and Bootmgr. For the second OS they use their own. Regardless of which manager is used, it is possible to make it work with another only through the BIOS.
Bootmgr is missing
This error indicates that there is no manifest on disk. It can arise in different situations:
- The file is damaged;
- The order of using files is incorrectly configured;
- Hard disk disconnected.
The solution to these problems is possible by setting the correct boot order in the BIOS. If the file is damaged, then the next paragraph will indicate the solution.
Interaction between Windows boot manager and BIOS
In general, it can be argued that the functions of the BIOS and bootmgr complexes are interrelated and somewhat SIMilar. The first one starts all the components of the computer, put them into operation and configures the ability to exchange commands between the user and the computer. The second then takes control and launches other system programs, which will be given control after. The following diagram most clearly illustrates the procedure for transferring control of a computer to the operating system.
The start order implies that when the BIOS is initialized, the system disk is turned on (not the disk partition, but the hard disk with the OS), where bootmgr is located, which is unloaded into RAM. Further, under the control of the Windows boot manager, OS components are launched and control is transferred to them.
What is Windows Boot Manager. how it works and how to disable it
Starting the operating system on a computer begins with the launch of the Windows boot manager, a boot manager for operating systems. This subroutine starts all the processes necessary for the normal functioning of the system.
Windows boot manager is a set of programs and commands responsible for booting the system and initializing computer components. Its work allows you to load the operating system (OS) on the computer. Since this is a complex of components, it is impossible to directly influence it. There is a special utility located in the “Download” section when you open “msconfig”.
Through this window, modules are connected or disconnected in the startup configurator, which changes the bootmgr settings (abbreviated name of the boot manager).
Boot manager features
When the OS starts, the following actions are performed:
- Initialization of computer components to work as part of the system;
- Writing the OS kernel to RAM;
- Initial configuration of a loaded kernel;
- Passing control to the kernel.
Next time the manager will be called only at system startup. It will be in standby mode while the computer is turned on.