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gillbatesjr

1 Rookie

 • 

14 Posts

33893

March 6th, 2023 18:00

Unable to boot from USB flash drive

When I select a USB flash drive from the boot device list in UEFI (BIOS) instead a system diagnosis test is run which completes after ~8 minutes. A message is then displayed thus: "Success Hardware scan complete with no issues. Your machine will restart and download cSOS for recovery".

Obviously this process is not booting from my flash drive.

Can anyone tell me what I'm doing wrong and what is a "cSOS for recovery"?? Why is the boot process not running?  And why is a system diagnosis test run?  TIA

1 person also has this problem

gillbatesjr

1 Rookie

 • 

14 Posts

March 7th, 2023 07:00

Thanks for the reply.

Further investigation revealed that I had to disable the 'Secure Boot' feature in UEFI prior to booting from the USB flash drive.. 

The bootable USB flash drive contained the Memtest86+ stand-alone memory tester program (Memtest86+ binary is not signed by Microsoft).

Obviously it would be much better to produce an error message plainly describing the actual problem (ie, "USB flash drive does not meet Secure Boot requirements" or some such message).

Hopefully my experience will benefit others.

Brad L (retired)

9 Legend

 • 

2.7K Posts

May 3rd, 2024 22:55

Possible Cause

The USB media is not signed for Secure Boot, so UEFI blocks it and defaults to diagnostics instead of booting from the USB.

Steps to Resolve

  1. Disable Secure Boot in BIOS — Restart and press F2 → Secure Boot → set to Disabled.
    • Save changes and reboot.
  2. Ensure the USB drive is bootable and formatted correctly (FAT32 for UEFI).
  3. Use F12 at startup to open the One-Time Boot Menu and select the USB device.
  4. If the USB still does not appear, recreate it using the official tool (e.g., Microsoft Media Creation Tool).
  5. Re-enable Secure Boot after completing the task for system security.

Still need Help?

  • Under warranty? Click the Get Help Now button at the bottom-right of this page to chat with Dell Support.

  • Out of warranty? You can request a service quote from Dell or consult a trusted technician for a hands-on diagnosis.

References

(edited)

AdrianG001

4 Operator

 • 

4K Posts

March 7th, 2023 03:00

If your Windows won't boot from USB, you can try many methods:
  • Check if your USB drive is bootable.
  • Check if the PC supports USB booting.
  • Change settings on a UEFI/EFI PC.
  • Check the file system of the USB drive.
  • Re-make a bootable USB drive.
  • Set the PC to boot from USB in BIOS.

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