Sep 23, 2019

Operating system not found in Windows 10

This is a screenshot of Acer V5 after the system restart after Windows 10 updates. The message shows "Operating system not found".

Current notebooks have two boot options which are legacy and EUFI compared to old models which uses BIOS only.

How to fix it:

1. Upon power on, press ESC key to enter BIOS.
(Other model uses different key such as F2 or DEL or F1)

2. Go to boot option and on boot mode then select legacy.

3. Press F10 and you should be able to boot normally.

4. In case boot mode already set to legacy, change to EUFI and press f10 (save and exit).

5. Finally go to boot mode again and change back to legacy BIOS.


Firmware is the piece of software that acts as an interface between the hardware(motherboard) and the Operating System. Legacy Mode refers to BIOS firmware. Basic Input/Output System(BIOS) was the first popular firmware for desktop PC introduced in 1975 by IBM for its CP/M OS. Even though it is still widely present, computers have evolved tremendously and BIOS is unable to provide advanced features of modern hardware.

Unified Extensible Firmware Interface(UEFI) is the successor to BIOS. UEFI uses the GUID Partition Table (GPT) whereas BIOS uses the Master Boot Record(MBR) partitioning scheme. GPT and MBR are both formats specifying physical partitioning information on the hard disk