I just installed Ubuntu MATE 18.04 from USB Flash drive by going to preview Ubuntu and double-clicking Install icon on the desktop. There is no prompt to remove USB bootable drive during installation - it just reboots from USB again. Removing the USB drive after “Installation Complete” message, ruins the installation and corrupts the image on USB drive.
I know how to handle this issue, but I thought it may be helpful for inexperienced users to have it fixed. I’m not sure if this is the right place to report issues like this.
Oh yeah, I noticed this too on my laptop: after the installation, I got to the black screen saying it was finished, where the “remove the installation media and press enter to reboot” is usually displayed but not this time. Had to turn power off, remove the USB key and on again. I was a bit surprised but had no issue afterwards, the installed system booted properly.
I’m surprised it broke everything for you: did you remove the USB key when on this black screen or when it was still displaying the graphical installer?
Also, I think I got the message properly when installing UM 18.04 in a VM, so the issue might be specific to some hardware.
I removed it before black screen, but after the message box with installation complete, rebooting system appeared in graphical installer. There was probably still some I/O to USB drive in progress. This was my fault, but I was conditioned by the same problem with Windows 10 install a while ago - infinite reboot to installation media loop.