I have a MacBook from 2017, first with Xubuntu 16.04 and since yesterday with Ubuntu 18.04 LTS. It's the only OS in my Mac and it worked fine until now.
Even when it had Xubuntu 16.04, since a week ago (so the problem is independent of the update), the system did not boot or reboot the first time I power it on.
I have to power it off pressing the button and after that (now with 18.04 LTS) it shows the GNU GRUB 2.02 menu where I can select several ways of booting Ubuntu (I tried them all with no result).
I press return to use Ubuntu as default and the system boots fine after that.
I tried boot-repair without result. The resulting URL is http://paste.ubuntu.com/p/3wZTsMwSjm/
Even when it had Xubuntu 16.04, since a week ago (so the problem is independent of the update), the system did not boot or reboot the first time I power it on.
I have to power it off pressing the button and after that (now with 18.04 LTS) it shows the GNU GRUB 2.02 menu where I can select several ways of booting Ubuntu (I tried them all with no result).
I press return to use Ubuntu as default and the system boots fine after that.
I tried boot-repair without result. The resulting URL is http://paste.ubuntu.com/p/3wZTsMwSjm/