I helped installing Ubuntu 18.04 in an Acer Aspire One cloud 14. Then I noticed the
No booting device error
I followed these instructions that recommended '“Select an UEFI file as trusted for executing”' and then I got a purple screen after reboot.
Picking the right order for the newly fixed boot (I left 'yes' in the description as in the image in the link) didn't work immediately, I had to disable secure boot to obtain the GRUB screen and form there picking *Ubuntu -the first option- didn't work. Most answers recommend to disable secure boot and apparently that fixed the error in the past.
In my case, I only can load Ubuntu if I pick the recovery option, pick recovery mode,
'update grub loader' and then resume the load of Ubuntu and login. I don't know how to fix since most old answers (for 16.04 or older) end with the solution given above, but how can I fix grub permanently?