I literally spent years trying to get this to work - without success - until now.
Acer obviously put considerable thought into designing a BIOS that would not support Ubuntu or dual boot.
The secret to doing this is to install Ubuntu the old fashioned way (just use the defaults, and don't let it install over the Windows OS). Jump through the usual hoops to install off a USB drive, or off a CD-Rom, if you have one. It'll go through the usual installation process, but . . .
On reboot, the usual option window won't show up. The machine will simply boot into Windows again, and will completely ignore your Ubuntu installation.
So now you'll go into the BIOS again.
Under "Main" ensure that "F12 Boot Menu" is enabled.
Under "Security" set a supervisor password. This will open up the blanked-out options on this page. Once you have set that password, on the same page go to "Select an UEFI file as trusted for executing."
Choose HDD0, or whatever the option is (there should be only one).
Now choose "EFI"
Now choose "Ubuntu" (it *should* be there!).
Now choose "shimx64.efi"
Give it a good name.
Press F10.
On reboot, repeatedly press F12 until the boot options come up. One should be Windows Boot Manager, and the other should be the good name that you gave shimx64.efi.
Choose that name.
Ubuntu will boot.
I got most of this information from this video: https://www.youtube.com/watch?v=iD3JtoSbfOo
Hope this helps.
