The main reasons why the message may appear Operating System Not Found are:
- The hard drive has crashed, or the partition table has been lost.
- BIOS/UEFI tries to boot from another hard drive, or a USB.
- A bad Secure Boot configuration, or secure boot.
- The operating system boot has been corrupted.
- Bad SATA configuration.
We know or assume the operating system is there on the drives. At least this is the situation where our PC it was there the last time we turned it off without any problem. Therefore, the first thing we do almost automatically when we see this error is to restart the computer. Either through the key combination Ctrl + Shift + Delete or with the corresponding button, we turn off and turn on again.
Once we have carried out this very common task to solve errors, it could be that the message disappears. But it can also be the case, it is quite likely that we will see it on the screen again, so we are going to see how to solve it. At first, the first thing we have to know is that, as indicated by the message, the problem is that the operating system cannot be found. From this we can deduce that it is the BIOS that cannot load this system.
Fix “Operating System Not Found” error
The reasons for all this can be various, hence we can also use various solutions. These reasons can range from a simple BIOS misconfiguration to a more serious problem related to partitions, for example. However, we recommend that before format the pc completely try any of the solutions presented below.
Check the drives connected to the PC
Normally, Windows is always installed on the internal hard drive. And this disk is the one that is registered in the BIOS to load as soon as we turn on the PC. However, it may have changed the operating system booting for some reason, and therefore we encounter problems when starting, such as the message Operating System Not Found.
We must make sure that the PC tries to boot the operating system from the hard drive where we have the operating system installed, and not from other drives. For example, if we have other hard drives, or even USB sticks or external drives connected to the PC, we must disconnect them all, leaving only the main drive, and try again.
Check the computer’s BIOS
Although we do not have access to the operating system, we can boot the BIOS. Here we will have to check two things, first, that the machine recognizes the hard drive. If so, we must also make sure that the drive in which we have the system installed, be it Windows or any other, appears as the primary boot drive. It must be taken into account that the way to enter the BIOS changes from one maker to another.
The BIOS is the operating system that manage motherboard and it works completely independently of the PC’s storage unit, so even if it is not formatted, we will always be able to access the computer to check whether it recognizes the storage unit or whether we want to change it to another or start from one USB drive in case we are forced to reinstall Windows.
Typically by pressing Esc, Delete, or one of the function keys during the boot process before the actual system loads. In addition, the BIOS menus also vary by computer. In this case we normally have to locate the tab Boots with the keyboard to navigate through these and locate the options mentioned above.
Reset the BIOS to its factory settings
If your machine does not recognize the hard drive, there are many possible causes, from a faulty drive, to a damaged whole, through a connector or a bad configuration. If we don’t know what’s going on, the only solution is to try to reset all the bios menu to their default values. This is also found among the menus of this, where we see an option at the bottom to set the default values or reset the BIOS.
On many occasions this is with the F9 key, so we will then be asked for a confirmation about this reset, we accept it and restart the PC. Once we have reset to the factory settings, it should automatically recognize the storage unit of the equipment as the main and only one to start the equipment. If this is not the case, we will have to establish it manually through the Boot menu as we have explained in the previous section. If we perform this process correctly, the “Operating System Not Found” message should have disappeared.
Fix system boot failures
Something we should know is that Windows is based on three elements to start the computer. These are the Master Boot Record or MBR, the DOS Boot Record or DBR, and the Boot Configuration Database or BCD. Therefore, if any of these registries become damaged or corrupted, it is very likely that the Operating system not found error will appear. To fix these boot elements we have to follow these steps, it is not complicated.
First, we need an external drive to install windows, where we use media creation tool Microsoft to create a Windows 10 installation, for example. We downloaded this from the . Next, we only have to follow the steps of the wizard in the program to create the installable unit.
When the bootable drive is ready, we use it to boot the PC, specify the language, keyboard, and time format. On the next screen we select Repair the equipment. Next, we go to Troubleshoot / Advanced options / Command Prompt. In the Command Prompt window we write the three commands which we show you below:
bootrec.exe /fixmbr bootrec.exe /fixboot bootrec.exe /rebuildbcd
Each command can take several minutes to complete. Once all the processes have finished, we restart the PC to see if it starts normally.
With Hiren’s BootCD
If using an installation unit does not solve the problem, we can try Hiren’s BootCD. Hiren’s BootCD is a bootable drive in ISO format with which we create a bootable USB that includes a large number of applications with which we can solve practically any Windows problem, not only with booting if the bootloader has stopped working, but also with the partitions, another reason why our may have stopped recognizing the storage disk where Windows is installed.
We can download Hiren’s BootCD from its web page that we can access by clicking on the following from where we will download the ISO file that will later become a bootable USB using the application. Next, we must modify the order of the boot drives of our computer so that, in the first place, it reads the USB drives connected to the computer. Hiren’s BootCD is a version of Windows 10 PE, and all the applications that are included to repair computers are located on the desktop, specifically in the folder Utilities. Inside, we find the applications organized in folders. The one we are interested in is the Repair folder.
All of the applications available on Hiren’s BootCD are completely free and do not include any in-app purchases to unlock additional features, making it one of the best tools available today for fixing any issue that a managed computer may encounter. by linux.
Turn UEFI Secure Boot on or off
Another section that we must take into account is that almost all current equipment is sold with the UEFI firmware and the corresponding Secure Boot activated. However, in some cases, this may not work as expected. For example, if Windows is installed on a GUID partition table, it can only boot in UEFI mode. At the same time if Windows 10 runs on an MBR disk, it will not be able to boot in UEFI mode.
It is for all this that, if we have the error that the operating system cannot be found, we can try to enable or disable the UEFI secure boot. This allows us to check if either of the two changes fixes it. The adjustments are made in the BIOS menu, normally the option is called Secure Boot and it is found in the Security tab of this section.
Activate Windows partition
There is also the possibility that the windows partition disabled at that time, something we can fix. We do this with the native diskpart function that comes with Windows. Again we start the PC with a USB installation as we saw in the previous step to start the computer with it.
Then we start the PC, but in this case we go to Repair the computer / Troubleshoot / Advanced options / Command Prompt. In the window that appears we will have to type the following commands:
diskpart list disk
At that moment, a list appears with all the drives connected to the PC, so we write down the drive number that interests us, usually the largest. We reintroduce these new commands:
select disk NUMBER
list volume
This will show us all the disk partitions that we have selected and we see in which partition Windows is installed, noting its number again. To finish, we type:
select volume NUMBER active
We restart the computer to see if the failure that we have told you about in which the BIOS does not detect the OShas finally been resolved.