This is the first time I've tried to install a dual boot Linux partition on a UEFI enabled machine, but I'm not even sure this is a UEFI problem.
The machine is an HP Z Book G5.
I created a Into 18.04.3LTS 64bit install USB stick with UUI and booted into Live Ubuntu no problem from it just to make sure Ubuntu ran OK.
I then choose the 'Install' option within the live running Ubuntu for no other reason than it saved a reboot.
I went through the initial choices including setting up the partitions as I wanted and choosing where to install grub and all looked ok.
I was also given the option of installing 3rd party drivers and had to select a secure boot (?) password to be able to install these.
Everything looked good and so I clicked to start the installation.
After literally a few seconds of the install running I got a message to say that the install had failed because it couldn't copy files off the disc. This was before any reboot or anything.
I rebooted and the USB install stick want recognised as bootable.
I recreated the install USB with UUI but it still wouldn't boot. Oddly at this point that stick wouldn't boot in another, much older (is non UEFI) machine either.
I created a new install USB on a new stick with UUI and the Z book wouldn't boot from that either.
I tried creating the boot stock with Rufus and eventually got a stick that would not ok on the other machine, but on the Z book it tries to bit of the stock but I get a message from the Linux boot loader that 'a serious problem occurred'.