I recently installed Ubuntu 24.04.02 to an external SSD drive from a flash drive, both plugged into USB ports on a desktop computer set up to boot first from any drive plugged into a USB port. At the end of the install, the screen says “Ubuntu 24.04.02 LTS is installed and ready to use. Restart to complete the installation or continue testing.” Below that is a green button that says “Restart now.” A problem with that is, there are now two bootable devices, the USB flash install drive, and the SSD drive on which Ubuntu is newly installed, plugged into USB ports. It is ambiguous or uncertain as to which drive the computer will boot from after the Restart button is clicked. Common sense dictates that the USB flash install drive should be unplugged from the computer before clicking the Restart button, to ensure the computer will boot from the external SSD drive. However, unplugging the USB flash install drive at that time causes a fullscreen terminal to appear with mulitple error messages scrolling up the screen. Clearly something is wrong, and the computer needs to be shut down or restarted at that point. However, the power button has no effect. I had to shut the computer down by unplugging the power cord. After I removed the USB flash install drive, plugged the power cord back in and turned the computer on, it booted normally into Ubuntu from the SSD drive plugged into a USB port. What if this had happened on a laptop computer? Unplugging the power cord would not have shut it down, because of the battery.
Curious at to what else can be done at the end of install, I repeated the installation. When the screen with the “Restart now” button appeared, I shut the computer down by clicking the mouse pointer on the power button in the upper-right corner of the Ubuntu screen. With the computer shut down, I unplugged the USB flash install drive, turned the computer on, and it booted from the SSD drive on which Ubuntu is newly installed.
At the very least, the screen at the end of the install should present the option to shut the computer down so that the install flash drive can be removed before rebooting, or at least mention that can be done by means of the power button in the upper-right corner of the screen. A better fix would be for the Ubuntu installer to allow the install flash drive to be removed without creating errors, prior to the user clicking the Restart button. Text on the screen could say “Installation media can be removed before clicking Restart.”