A bootable device not detected showing on first boot after installing 18.04

I have installed ubuntu 18.04 on my 500gb hard drive using usb stick. no partitions done, used entire disk. Installation was successful. And, on reboot(first boot) it shows A bootable device has not been detected. But, I can boot to ubuntu 18.04 after selecting boot device(usb) from boot menu. How can I load OS without selecting hard drive from boot menu.

1. may be MBR is stored in usb.




2. used startup disk creator for creating bootable usb

You have UEFI boot enable on your device and you installed Ubuntu on legacy mode.

You need to change boot options from UEFI to Legacy. Refer your manufacturer guide to access BIOS Settings.