Error An operating system wasn’t found - what to do. What does the Operating System not found error mean? Basic BIOS settings

Very often, when Windows 10 refuses to start, the error Boot failure appears on the screen, as well as An operating system wasn’t found. Press Ctrl+Alt+Del to restart. The reasons for these errors are the same, and the methods for eliminating them are also similar.

Both of these errors can appear in the “ten”. For example, when deleting the bootmgr file on Legacy operating systems, the first error appears, and when the entire partition with the bootloader is destroyed, the second error appears.

Before you begin troubleshooting, you must carry out the manipulations that are written in the text of the notification, and then restart the computer. The first step is to disconnect from the PC all drives that do not contain the operating system. These could be flash drives, optical media and third-party hard drives. In addition, this category includes everything that is connected via USB, except for controls.

In addition, you need to check that the startup is performed from the first hard drive or Windows file Boot Manager for UEFI systems. In this case, you need to go to the BIOS and check the startup order of the devices. To do this, it will be easier to use the Boot Menu. If, when using it, the “ten” starts up normally, then you should go to the BIOS and change the parameters.

If this does not bring the desired result, then such errors occur for more serious reasons, so it will be a little more difficult to eliminate them.

Setting up the tens bootloader

As can be understood from the above, artificial occurrence of errors is quite common if you independently corrupt the contents of a hidden section reserved by the operating system or with the operating system loader. In this case, if such errors occur, you should try to restore the OS bootloader.

This can be done quite simply. You need to get a bootable drive
or a recovery disk with an operating system of the same bit size that is installed on the computer. It is worth noting that a similar drive can be created on another computer.

Next, you need to boot your PC from this drive. If you are using an installation image of the system, then you need to go to the recovery environment. To do this, click “System Restore” on the language specification screen.

Here you need to specify “Troubleshooting”. In the next window you need to click “Advanced options”. After this, you need to click “Startup Repair”. Then you need to select the operating system version.

After this it will start automatic search problems with the bootloader and its recovery. This feature works perfectly and in most cases no user intervention is required.

If this does not bring the desired result, and the error again appears on a black screen, while loading must be performed from the required drive, you should try to resuscitate the bootloader in manual mode.

In addition, problems with the bootloader may occur after turning off one of the hard drives from the PC. In this case, the bootloader must be located on this drive, and the operating system on another. In this case, you need to look down in a certain way.

The first step is to allocate some space at the beginning of the disk with the operating system for FAT32 for UEFI or NTFS for Legacy. You can do this using the free MiniTool Bootable Partition Manager image. After this, you need to restore the bootloader manually using bcdboot.exe

Error starting "ten" due to problems with the hard drive or SSD

If no manipulations to resuscitate the bootloader help eliminate these errors in the “top ten”, then they may be affected by malfunctions with the hard drive or lost files.

If there is an assumption that one of these things happened, and this can be influenced by power failures, hard drive defects, etc., in this case it is necessary to carry out several manipulations.

The first step is to reconnect the hard drive or solid state drive. To do this, you need to disconnect the SATA cables and power cords from the motherboard and hard drive. You can also disconnect the remaining wires.

Then you need to boot into the recovery environment, and using the command line, you need to scan the hard drive for errors. In addition, it is possible to reset the system from a third-party drive. There is also an option to eliminate the error by installing the operating system from scratch, while performing formatting.

That's basically all possible reasons occurrence of problems and methods for eliminating them. It will be very good if we can fix the problem simple shutdown drives and bootloader recovery. If this does not help, then you need to reinstall the operating system.

One of the most terrible user errors is the one that appears when turning on the computer and tells us, on a black BIOS screen, that "". When this message appears, our system will not be able to boot, and the only way out is to restart the computer by pressing “ctrl+ alt+del”, and you will most likely see this message again An operating system wasn't found. Try disconnecting any drives that don't contain an operating system. Press Ctrl+ Alt+Del to restart.

The problem with the error is that the operating system is not displayed and therefore the BIOS cannot boot the Windows system. The reasons for this error are very varied: from a simple configuration error in the BIOS to a more serious problem that, in the worst case, forces us to completely format the computer. Therefore, we will analyze the main reasons and their solutions to eliminate the error "" ( An operating system wasn't found).

Disconnecting external USB devices from the computer

If your computer has multiple internal hard drives, external and USB flash drives, it is likely that The BIOS is trying to find the operating system in the wrong place. Consequently, not detecting the Windows system, it displays the error “Not found operating system".

• To solve this problem, you need to disable everything external devices storage devices connected to the USB ports and try again. We can also check our optical drive to make sure it's not trying to load the wrong DVD.

If after doing this the problem is still not resolved, the next step is to go to BIOS settings.

Changing BIOS boot priority

Enter the BIOS configuration by pressing the F2, F12 or Delete buttons. After that, go to the configuration section Boot and put it first in the column Priorityhard drive on which the working and main operating system is Windows. IN different versions BIOS is called differently, but you are looking for the word with the combination Priority, which means “priority boot”. Here are some titles from different BIOS: Hard Disk Priority, Boot Device Priority, Hard Disk Boot Priority.

May be useful:. There you will find approximately where to look Priority, but don't forget that there is a manual in there for the flash drive.

After you have set the boot priority from hard drive on which your system is located, do not forget to save the settings using the F10 button and restart the computer to make sure that “the system is found when you turn on the computer.”

Enable or disable Secure Boot

If you are using modern computer with an operating system such as Windows 8 or Windows 10, then perhaps the reason why our Windows does not start is in incorrect UEFI Secure Boot configuration.

Go back to BIOS, find the configuration section Secure Boot (Secure Boot) and deactivate it or activate it if it is disabled to check if the “Operating system not found when booting the computer” error disappears.

In different BIOS versions or UEFI, the location of the settings looks different, but in any version of the BIOS you look for the column Secure Boot, try disabling or enabling.

Reset BIOS to factory settings

At the bottom of the BIOS menu you will see a key for default settings or reset BIOS . On my car this is F9. Confirm your decision when prompted and restart your computer.

If you haven’t found an example button like F9 to reset settings to factory settings, then look for the line Load Setup Default and reset the BIOS.

If your hard drive with the operating system is placed first, but the computer still does not boot, it is possible that some of the initial sectors of the drive have been damaged, such as main boot record (MBR), DOS boot entry(DBR) , or Boot Configuration Database(BCD).

Repairing these sectors is quite simple. All we need is to start the computer from USB or Windows DVD. You can, for example, or just start with and select “System Restore” when installing Windows.

Type the following commands into CMD in order by pressing enter. Each command may take time to complete.

• bootrec.exe /fixmbr
• bootrec.exe /fixboot
• bootrec.exe /rebuildbcd

Activate the Windows partition

It is possible that the partition on which Windows is installed is disabled. You can fix this using Windows' native diskpart tool. To complete the next steps, you will again need a USB stick for Windows installations. Run the command line as described above, via a recovery disk or Windows installation flash drive and enter the following commands in the command line:

• diskpart- Launch the tool.
• list disk- List of connected drives to the computer.
• select disk 0- Select the hard drive on which you want to activate the partition. In my case, the main hard drive is 0.
• list volume- Shows partitions on the selected hard drive.
• select volume 2- Choose local disk to activate. Choose the one where the widows system itself is installed.
• active- Activate the section.

Restart your computer and make sure the error when turning on the computer disappears An operating system wasn't found. Try disconnecting any drives that don't contain an operating system. Press Ctrl+ Alt+Del to restart, which means operating system not found, click to reboot ctrl+alt+del.

Sometimes when reinstalling the operating room Windows systems or when moving from more new system the old error occurs: " An operating system wasn't found. Try disconnecting any drivers that don"t contain an operating system"Also, this error may occur due to improper intervention in the hidden boot hard section disk. In this manual, you can learn how to resolve the “An operating system wasn’t found” error.

In Windows 7, 8 or 10, the system boots from a hidden partition (reserved by the system). Each of these operating systems hidden section has a different volume: in Windows 7 - 100 MB, in Windows 8 - 350 MB, in Windows 10 - 500 MB.

When installing the system, you probably could see these sections.

The hidden partition contains operating system boot files. If for some reason this partition becomes inactive, the operating system will not boot and you will see the error “An operating system wasn’t found”. Try disconnecting any drivers that don"t contain an operating system".

To fix this problem you only need to make the section active.

The hidden section should always be the main and active one. This is an ironclad rule, thanks to which the BIOS understands that the download files are located on the specified partition. Let's see what is stored on this hidden partition as an experiment. First, let's go to "Disk Management"

Since I use Windows 7, it is clear that I have 100 MB reserved by the system. If you assign a letter to this hidden partition, it will be displayed in the “Computer” window, provided that the item “display hidden protected system files” is activated in the system settings.

As you can see on this disk there are boot files OS.

Below we will look at two ways by which the error will go away and the system will boot again in normal mode. By the way, all manipulations can be carried out both on Windows 7 and on Windows 8 and Windows 10.

Method 1. How to make a partition active using Acronis Disk Director

First you need to create an Acronis Disk Director boot disk if you don't have one. The image can be downloaded on the Internet and then burned to disk. If you don’t know how to do this, you can read the article. Next, we boot from this media.

The hidden section should always be active, as I wrote above, that is, it should be marked with a red flag in the program. As you can see below, the hidden section is inactive,

To fix this, click right click mouse over the section and click on the item “Mark as active”,

For the changes to take effect, click on the button with the “Apply pending operations” checkbox.

After completing the operation, you can see that the partition has become active.

Now all that remains is to restart the computer. If everything is done correctly, the system will boot and you will be taken to your usual Desktop.

Method 2. How to make a partition active using the Windows installation disc

If you don’t have a disk with Acronis Disk Director at hand, don’t despair. You can do without this program, however installation disk we still need it with the operating system. We boot from it by pressing any key on the keyboard,

Mass transition to tenth Windows version showed a large number of vulnerabilities of this system, which are less common in the legendary seven. It is in 10 that users most often catch the error “An operating system wasn’t found,” which literally translates as “The operating system was not found.” To be fair, it is worth noting that it also appears during normal system startups on Windows 7 or 8.1.

Reasons for “no operating system”

Unfortunately, no one knows the specific cause. According to some reports, the cause of the bug lies in contradictions between different disk partitions on the hard drive (HDD, SSD). When it is not possible to extract the necessary information or something prevents the bootloader from starting, “An operating system wasn’t found. Try disconnecting any drives that don’t contain an operating system. Press Ctrl+Alt+Del to restart." Also, the reasons include a banal critical error in Windows.

Error An operating system wasn’t found in Windows

Technical breakdowns have also not been canceled; very often the user cannot even load the BIOS.

What to do if there is an error

When the message “Operating system not found” appears, nothing good can happen. Everything is really very bad. That is, simple ways there is no solution here. You will have to tinker a lot with the operating system to restore it, and sometimes even this cannot be done - there are no signs of startup. The only plus is the low probability of the computer itself breaking down; this is still more of a software problem.

Did you understand the computer?

If the computer has recently been disassembled technical reasons(boards changed, HDD) or cleaned from dust, then you should definitely double-check the reliability of the connections on the hard drive (power supply, sata). Disconnect each cable and re-insert it into the grooves more efficiently. In rare cases, it is recommended to double-check the integrity of all wires leading to the hard drive. Also, don’t forget the classic – remove the Bios battery.

Windows 10 boot disk

We will need an installation disk of your Windows 7/8/10, or create bootable USB flash drive. Set the boot priority (Boot tab) for the disk or flash drive in the BIOS. With its help you will need to try to revive the OS. There is a very good function for this, and it is called “System Restore”. It can be found when installing the operating system after clicking “Next” once. There will be a corresponding item below.

Thanks to clear signs it will not be difficult to understand. To be on the safe side, try several options; sometimes using a recovery point may not work. Then go to the point where the system image will be used.

Command line

This method helps with the top ten for sure. Go to “Recovery”, there we click on “Troubleshooting”, and then go to “Advanced options”. Choose Command line. Next, enter the following commands:

1. DISKPART – waiting for loading.
2. List Volume – a numbered list of your partitions will appear, indicating the system one.
3. Select Volume 1* – the number means the number of your system disk.
4. Active
5. Assign
6. Exit and restart your computer.

It is possible to execute slightly different commands. Here are video instructions, try them if the above don't help.

Reinstalling the OS

It was impossible to avoid this point. If the above methods are not effective, then there remains clean reinstallation Windows. The only option with the largest share of solutions to the error “An operating system wasn’t found.” Try disconnecting any drives." It is advisable to format the partition where you are going to install the OS.

More options

There is a small chance that this will help you and save you from going to service center, but you can still try.

1. Remove all installed drives from the PC. There shouldn't be any flash drives. Disconnect the additional hard drive, mice and other devices.
2. It is worth considering the option of a broken connector on motherboard. Check the hard drive on another PC to see if the problem is there or something else.
3. At reinstalling Windows use the licensed version, but before doing this, be sure to format the entire hard drive.

That's all the options. If you have little programming experience, do not try to work with BIOS settings yourself, which are sometimes mentioned we're talking about in the forums. It is better to entrust this matter to an IT specialist.

1. Symptoms of the problem

When computer is powered up, the following error message appears:

An operating system wasn't found. Try disconnecting any drives that don't contain an operating system. Press Ctrl+Alt+Del to restart (white-on-black letters in text mode and blinking cursor):

2. Normal boot sequence

The rest of this article refers to Windows 10, but all information below applies to Windows 8/8.1 as well. (Windows 7 and Windows Vista never emit this error, instead they emit "BOOTMGR is missing" .)

Normally Windows 10 boots as shown below:

1. Master Boot Record scans partition table for active partition, then it loads 1st sector from active partition, verifies 55 AA signature, and transfers control to Boot Sector.
2. Boot Sector loads 15 additional sectors from the beginning of disk (Volume Boot Record) and transfers control to first additional sector of VBR.
3. Volume Boot Record loads BOOTMGR file from root directory of boot partition into the memory and transfers control to it.
4. BOOTMGR loads Boot\BCD registry hive and displays boot menu. BOOTMGR is able to run memory test and set safe mode boot flag per explicit user request. But normally, it loads winload.exe when computer boots normally (cold startup) or winresume.exe (when computer resumes from hibernation).
5. Winload.exe opens SYSTEM registry hive, gets list of drivers, loads NTOSKRNL.exe, loads drivers (*.SYS files) and transfers control to NTOSKRNL.exe.
6. Winresume.exe loads memory dump from hiberfil.sys and transfers control to it.

3. Defect in the boot sequence which leads to BOOTMGR is missing error

Defect in the boot sequence which leads to "An operating system wasn"t found" error is shown below:

1. BIOS loads 1st sector from HDD (Master Boot Record), verifies 55 AA signature and transfers control to Master Boot Record.
2. Master Boot Record scans partition table for active partition. There is one active partition, so Master Boot Record loads 1st sector from active partition (Boot Sector), and transfers control to it.
3. Boot Sector loads the rest of Volume Boot Record and VBR tries to find BOOTMGR at the root directory of boot partition but fails because "BOOTMGR" file does not exist or not readable.
4. The rest of the usual boot events do not happen.

4. How to fix "An operating system wasn"t found" error

1) Download Emergency Boot Kit and deploy it to USB thumbdrive according to the instructions, then set up your BIOS to boot from USB thumbdrive. You need full version of Emergency Boot Kit to actually write changes to the disk, but it"s recommended to try demo version to make sure there are no hardware incompatibilities.

2) Boot into Emergency Boot Kit:

3) Run File Manager from the main menu:

4) Press Alt+F1 and choose your boot partition from the menu. For Windows 10 and Windows 8/8.1 this partition should have "System Reserved" volume label and is expected to be small (100-500MB). Use UP and DOWN arrow keys and ENTER to navigate the menu:

5) In this example, BOOTMGR file is missing from boot partition. If it exists in your environment, delete it (set cursor to the file using arrow keys UP and DOWN and then press F8). If BOOTMGR file is not deleteable, then rename it (for example, to BOOTMGR.OLD by pressing F6 key):

6) Insert Windows 10 installation USB thumbdrive to any of your computer's USB ports and press Alt+F2. Choose Windows 10 installation USB thumbdrive drive from the menu using UP and DOWN arrow keys:

(Alternative approach: if don"t have Windows 10 installation USB thumbdrive, then you can recover a copy of this file from \Windows\Boot\PCAT folder on your system partition)

8) Press TAB key to switch input focus to the right panel and navigate to the BOOTMGR file:

9) Press F5 to copy BOOTMGR to the left panel. Confirm with ENTER key: