An operating system wasn’t found. Try disconnecting any drives that don’t - what to do. Repairing the Windows bootloader. BIOS settings and boot options

Two errors on a black screen when Windows 10 does not start - “Boot failure. Reboot and Select Proper Boot device or Insert Boot Media in selected Boot device ”and“ An operating system wasn’t found. Try disconnecting any drives that don’t contain an operating system. Press Ctrl + Alt + Del to restart ", as a rule, have the same reasons, as well as methods of fixing, which will be discussed in the instructions. In Windows 10, one or the other error may appear (for example, if you delete the file bootmgr on systems with Legacy boot, An operating system wasn't found appears, and if you delete the entire partition with the bootloader, the Boot failure error appears, select proper boot device). It may also come in handy: - all possible causes and solutions. Before proceeding to fix errors using the methods described below, try what is written in the text of the error message, and then restart the computer (press Ctrl + Alt + Del), namely :

• Disconnect all non-operating system drives from the computer. This refers to all flash drives, memory cards, CDs. Here you can add 3G-modems and USB-connected phones, they can also affect the startup of the system.
• Make sure to boot from the first hard drive or from the Windows Boot Manager file for UEFI systems. To do this, go to BIOS and in the boot parameters (Boot) look at the order of boot devices. It will be even easier to use the Boot Menu and, if Windows 10 started normally when using it, go to BIOS and change the settings accordingly.

WIndows 10 won't load - black screen

What needs to be done after this:

Problem when creating a new section and finding an existing one

Recovery tools will automatically try to find problems with the bootloader and repair it. In my tests, the automatic fix for Windows 10 startup works just fine and for many situations (including formatting the partition with the bootloader) no manual steps are required.

A variant of problems with the bootloader is also possible after disconnecting one of the hard drives from the computer - in cases where the bootloader was on this disk, and the operating system was on the other. In this case, a possible solution:

1. At the "beginning" of the system disk (ie before the system partition), select a small partition: FAT32 for UEFI boot or NTFS for Legacy boot. This can be done, for example, using the free bootable MiniTool Bootable Partition Manager image.
2. Restore the bootloader on this partition manually using bcdboot.exe (instructions for manual recovery of the bootloader were given just above).

What is the hosts file in Windows 10

Sometimes, when reinstalling the Windows operating system or when switching from a newer system to an old one, an error occurs: " An operating system wasn "t found. Try disconnecting any drivers that don" t contain an operating system". Also, this error can occur due to improper intervention in the hidden boot partition of the hard disk. In this manual, you can learn how to fix the error" An operating system wasn "t found".

In Windows 7, 8 or 10, the system is booted from a hidden partition (reserved by the system). For each of these operating systems, the hidden partition has a different size: in Windows 7 - 100 MB, in Windows 8 - 350 MB, in Windows 10 - 500 MB.

During the installation of the system, you may have seen these sections.

The hidden section contains the operating system boot files. If this section for some reason becomes inactive, then the operating system will not boot accordingly 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 just need to make the section active.

A hidden section should always be primary and active. This is an iron rule, thanks to which the BIOS understands that the download files are located exactly on the specified section. Let's take a look at what is stored on this hidden section as an experiment. First, let's go to "Disk Management",

Since I am using Windows 7, it can be seen that I have 100 MB Reserved by the system. If you assign a letter to this hidden section, 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, this disk contains OS boot files.

Below we will consider two ways, thanks to which the error will go away and the system will reboot in normal mode. By the way, all manipulations can be performed 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 a bootable Acronis Disk Director disk, if it does not exist. The image can be downloaded from the Internet and then burned to disk. If you do not 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,

We fix this - right-click on the section and click on the item "Mark as active",

To make the changes take effect, click on the button with the "Apply expected operations" checkbox.

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

Now it remains to restart the computer. If everything is done correctly, the system will boot and you will be taken to your familiar 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, then don't despair. You can do without this program, but we still need an installation disk with the operating system. We boot from it by pressing any key on the keyboard,

There are many errors due to which Windows will not start. It's a very sad story and you have to deal with it. In this article, I will analyze another error - “An operating system wasn t found. Try disconnecting any drives that don t contain an operating system. Press Ctrl + Alt + Del to restart "... We see that to continue, you need to press the appropriate key combination, but since you got here, you could not fix the problem. Let's try to deal with this difficulty.

Why does An operating system wasn t found error appear?

This error says that the operating system was not found and you need to disconnect all disks containing it. So to speak, a little hint, then the problem may be related precisely to the drives. Of course, this does not always happen, that is, it is not even physical damage to the disk. Most likely, due to user manipulation while booting the system, the BIOS was unable to detect the system boot record. In one of the articles about the error, a similar case was described.

If the problem is in the disk, then the connected cables may have been damaged or disconnected. This should be checked first. In addition, try turning off all external devices - flash drives, external hard drives, card readers and modems. In short, everything that is connected via USB and has the concept of a drive. And also, as it was recommended from the text of the error - disconnect other disks on which the system is not installed, if there is only one disk, then we skip this moment.

How to get rid of the error An operating system wasn t found

Of course, I have already given a couple of tips a little higher, but I will repeat. Since many users simply do not read carefully, as I noticed.

Disconnect all external devices that are connected via USB, especially memory drives;

Check if the cables and other cables are well connected to the drives. Check the connections of other components. Check the integrity of the equipment in general.

Log in and check for a hard drive under Boot... If it appears, then the drive is working, but the problem may be with the Windows boot record. Try it. I almost forgot. Also look at the Boot tab for the correct location of the boot devices. The disk on which the system is located must come first.

Also, the presence and health of the disk can be checked through.

How to repair Windows bootloader

If you checked everything that I asked you about above, but the error still appears, then you can safely blame corrupted Windows boot record... How it got damaged is unknown, perhaps the user himself carried out some actions in the system that brought it to such a state.

I already wrote about bootloader recovery in these articles:

You need to create a bootable Windows USB stick. It is desirable with the same version that was installed, but this is not necessary.

Here are the articles on how to create a bootable Windows USB stick:

A bootable USB flash drive with the system is a full-fledged distribution from which you can install and reinstall Windows, but in this case we do not need this. Insert the USB flash drive and boot from it via BIOS or Boot Menu.

The Windows 10 boot menu should appear on the monitor screen (I have it). In the window that appears, click on the option "System Restore".

A blue window appears, where we select the section "Troubleshooting" or "Diagnostics".

Now we select the item Startup Repair.

This method is automatic and should do all the painstaking work for you, but, as we know, automatic methods are not as good as we would like. If you have coped with the problem, then I congratulate you, be sure to unsubscribe in the comments. Did not work out? Then try other methods. I indicated the links to them just above.

Additional command line method

To get rid of the an operating system wasn t found error, you need a command line. She is in additional parameterswhere you selected automatic bootloader repair.

Or, where you select the Windows installation section, press the combination Shift + F10 and the command line is highlighted.

After activating the utility, we enter one more command - list disk... It displays all connected drives.

Now you need to make sure that on the disk where the operating system is installed (not a partition, but a full disk). Find the GPT column in the plate. If there is an asterisk in front of the required disk, then this is GPT partitioning, if not, then MBR.

Exit diskpart by typing the command exit.

MBR Partitioning Actions

It would be necessary to find out the specific section where the operating system is installed. We use CMD again and enter the following command:

dir c:

Perhaps, when entering the command, you did not find the line with Windows, then we use another letter, for example, like this:

dir e:

Let's say the system is, in our case, on section C according to the standard. Then we put in this:

bcdboot C: \\ Windows / S C:

If everything is correct, you will see a notification about the successful creation of the boot data - "Boot files successfully created".

That's not all.

1. Writing to CMD again - diskpart;
2. We register list disk;
3. We write select disk 0, where 0 is the disk number, which you may have different;
4. Then we write list volume;
5. Select volume N - where N is the number of the section where the system is installed;
6. Active - activate the section;
7. Exit - exit.

Actions for GPT Partitioning

In the same way, as with the MBR markup, we define the partition with the OS with the dir command:

dir c:

or another letter.

We enter the following commands in the following order:

1. diskpart;
2. list disk;
3. select disk 0 - the number of the disk with the operating system;
4. list partition - output of sections. Let's define a system labeled System;
5. select partition N - indicate the number of the OS section;
6. assign letter \u003d V - assign the letter V;
7. exit - exit.

After exiting the disk utility, write the following commands:

1. cd / d S: \\ EFI \\ Microsoft \\ Boot \\
2. ren BCD BCD.bak
3. bcdboot C: \\ Windows / l ru-ru / s m: / f UEFI

This should help clear the An operating system wasn t found error. Thus, we have restored the boot record of Windows 10 or another system. I hope this method helped you. If it did not help, then above I indicated links to restore the bootloader in other ways, try them too. And if not at all, and even instructions from other sites do not help, then reinstalling Windows will help you.

The massive transition to the tenth version of Windows showed a large number of vulnerabilities of this system, which the legendary seven is less prone to. 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”. For the sake of justice, it should be noted that it also appears during normal system launches on Windows 7 or 8.1.

Reasons for the "absence of an operating system"

Unfortunately, no one knows the exact cause of the occurrence. According to some reports, the reason for the bug lies in the contradictions between different partitions of the disk on the hard drive (HDD, SSD). When you cannot 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.

An operating system wasn’t found error in Windows

Nobody canceled technical breakdowns either, very often the user cannot even load the BIOS.

What to do in case of an error

When the message "Operating system not found" appears, nothing good is expected. Everything is really very bad. That is, there are no simple solutions 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 launch. The only plus is the small probability of damage to the computer itself, it is still more of a software problem.

Did the computer understand?

If the computer has recently been dismantled for technical reasons (changed boards, HDD) or was cleaned of dust, then you should definitely double-check the reliability of the connections on the hard drive (power supply, sata). Disconnect each ribbon cable and re-insert it into the grooves with better quality. In rare cases, it is recommended to double-check the integrity of all wires leading to the hard drive. Also, do not forget the classics - we take out the Bios battery.

Windows 10 boot disk

We will need your Windows 7/8/10 installation disc, or create a 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 reanimate the OS. There is a very good function for this, and it is called System Restore. It can be found during the installation of the operating system after one click "Next". The corresponding item will be below.

Easy to understand directions make it easy to understand. For reliability, try several options, sometimes using a restore point may not work. Then go to the point where the system image will be used.

Command line

This method helps on the top ten for sure. Go to “Recovery”, there we click on “Troubleshooting”, and there we go to “Additional parameters”. Selecting the Command Line. Next, enter the following commands:

1. DISKPART - waiting for loading.
2. List Volume - a numbered list of your partitions will be released, 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.

Some other commands can be executed. Here is a video tutorial, try them if the above doesn't help.

Reinstall OS

It was impossible to avoid this point. If the above methods are not effective, then a clean reinstallation of Windows remains. The only option with the largest share of solutions is 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 the 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 the motherboard. Check your hard drive on another PC to see if the problem is there or something else.
3. When reinstalling Windows, use the licensed version, but before that, be sure to format the entire hard drive.

These are all options. If you have little programming experience, do not try to work with the BIOS settings yourself, which are sometimes discussed 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 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: