Comment 24 for bug 1867092

I can also confirm this bug for Kubuntu 18.04 LTS at an older Apple iMac 8,1 computer. The solution seems to purge shim and then reinstall grub.

It would be really great if the corresponding devs can fix this issue by add a simple check (for an Apple EFI environment) before shim is installed. Or it may be also possible to make shim aware that there also exists non Secure Boot capable UEFI systems. (So far I know, Apple introduced the Secure Boot feature not before 2017.) On such nun Secure Boot compliant systems shim only has to be inactive and quiet. ;-)