I currently have a Windows 10 laptop that I am trying to reformat to make it run CentOS 7. The laptop does not have a CD/DVD drive, so I am trying to use a flash drive to reformat it. On Windows, I have used diskpart to clean, create partition primary, and format fs=fat32 on a flash drive. Afterwards, I simply xcopy everything from the DVD ISO file (mounted on my file system) over to the flash drive. At this point, my laptop recognizes the USB as bootable, but when attempting to boot, I get the error message "An operating system wasn't found. Please try disconnecting any drives that don't contain an operating system." Am I missing something stupid?

  • making a bootable usb is not simply copying file. a boot partition is needed in order to tell bios which file to boot upon. finding an usbcreator is quiet easy. – Archemar Dec 13 '15 at 9:42
  • @Archemar: Creating a primary partition makes the USB bootable. From there, you just need to tell the USB what to boot by copying the files. A USB creator isn't magic. Also, as I mentioned, the USB is bootable. – R_Kapp Dec 13 '15 at 12:36

The issue was that somehow, the BIOS had defaulted to trying to boot in Legacy mode. Changing that to UEFI mode caused the boot to work fine.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.