Ubuntu Server won't start on another PC?

Question

linux

Hello, this is the situation, I have two PCs.
On one of them, my worker, I pulled out all the disks, put in a 120GB ssd and a flash drive and ubuntu server 20.4.1.
Installed, configured everything, everything works.

Then I turned everything off and moved this ssd with ubuntu server to another computer.
The ssd sees everything in the bios.
When loading, the underscore (cursor) in the upper left corner just blinks and nothing happens.

I insert everything back into my computer, everything works. What could be the problem?

If you take a hard drive with Windows and insert it into this second computer, then everything works. But ubuntu doesn't load... It flashes and that's it...

Answer 1

Most likely, the bootloader is installed on a USB flash drive or on another disk that was in the computer at the time of installation. Try in the computer that does not start, put both an SSD and a USB flash drive / disk. Most likely it will start. You need to install a bootloader on the SSD. Or, as they wrote in the comments, it's UEFI. Reinstall in legacy and everything will work.