CompTIA A+ Core 1 (220-1201)Hardware and Network TroubleshootingHard
A desktop computer displays the message 'Operating system not found' during boot. The technician verifies in BIOS/UEFI that the correct drive is set as the first boot device. Which of the following is the MOST likely next troubleshooting step?
- AReplace the power supply unit
- BUpdate the graphics card driver
- CReseat the RAM modules
- DBoot from installation media and repair the boot sector/MBR
Show answer & explanationAnswer & explanation
Correct answer: D. Boot from installation media and repair the boot sector/MBR
With the correct boot device already confirmed in firmware, an 'Operating system not found' error typically indicates a corrupted boot sector, MBR, or boot configuration data, which can be repaired by booting from installation/recovery media and running boot repair tools.
Why the other options are wrong
- A. A failing PSU would likely prevent the system from powering on or POSTing at all, not just fail to find an OS.
- B. A graphics driver issue would not prevent OS detection at the boot level, since drivers load after OS handoff.
- C. RAM issues typically cause POST failures or beep codes, not a specific 'OS not found' message.
OS Not Found Boot Error
This error occurs when firmware cannot locate a valid boot loader/MBR/GPT boot record on the designated boot drive, even if the correct drive is selected.
- Confirm boot order in BIOS/UEFI first
- Corrupted MBR/boot sector is a leading cause
- Repair using tools like bootrec (Windows) from recovery media
Memory trick: 'No OS Found, Fix the Record.'