I have this very weird problem with my Ubuntu installation. I installed Ubuntu on an external hard drive (Seagate 2 Terabytes usb3) and everything seems normal. But when I unplug the external hard drive and plug it again and then start the computer, I cannot boot from this external hard drive. Do you know how can I resolve this issue? Thanks!
Note: I know I can repair the boot by launching bootrepair utility, but that's not something I want to do everytime I unplug my external hard drive. Note2: Changing the harddrive isn't something I want to do. I had CentOS on it before and it worked just great.