Updating Fedora 26 -> 27 fails - "problem with installed package grub2-efi"

[Christopher Ross]

I'm trying to upgrade my x86 laptop to Fedora 27 but consistently get 
the following:


root@nellie 07:54:07 ~ # dnf system-upgrade download --refresh 
--releasever=27
Before you continue ensure that your system is fully upgraded by running 
"dnf --refresh upgrade". Do you want to continue [y/N]: y
RPM Fusion for Fedora 27 - Free - Updates 81 kB/s |  39 kB     00:00
Last metadata expiration check: 0:00:00 ago on Fri 17 Nov 2017 07:55:33 GMT.
Error:
  Problem: package grub2-efi-1:2.02-0.40.fc26.i686 requires grub2-tools 
= 1:2.02-0.40.fc26, but none of the providers can be installed
   - grub2-tools-1:2.02-0.40.fc26.i686 does not belong to a distupgrade 
repository
   - problem with installed package grub2-efi-1:2.02-0.40.fc26.i686
root@nellie 07:55:38 ~ #




If I try removing grub2-efi in the hope that the upgrade will then 
proceed I run the risk of leaving the machine totally unbootable.

Useful suggestions will be gratefully received.

Many thanks,
Chris R.