Comment 3 for bug 1786090

Shim-signed failed to install. Here's the terminal output:

root@cedric:~$ sudo apt install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up shim-signed (1.34.9.2+13-0ubuntu2) ...
Installing for x86_64-efi platform.
Could not delete variable: Invalid argument
grub-install: error: efibootmgr failed to register the boot entry: Block device required.
dpkg: error processing package shim-signed (--configure):
 installed shim-signed package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 shim-signed
E: Sub-process /usr/bin/dpkg returned an error code (1)