Hello,
Yesterday, I turned on a computer I've not used for a while. This little machine runs the latest LTS version and is kept up to date.
So the first thing I did was to launch "Software updates" to get the latest packages.
Everything was fine except that the Grub update did not install and gave this messages :
Code:
This error could be caused by required additional software packages which are missing or not installable. Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time.
Transaction failed: Package dependencies cannot be resolved
 The following packages have unmet dependencies:

grub-efi-amd64-signed: Depends: grub2-common (>= 2.02~beta2-36ubuntu3.31) but 2.04-1ubuntu26.12 is to be installed
grub2-common: Depends: grub-common (= 2.04-1ubuntu26.12) but 2.04-1ubuntu26.12 is to be installed
              Depends: libc6 (>= 2.28) but 2.31-0ubuntu9.2 is to be installed
              Depends: libdevmapper1.02.1 (>= 2:1.02.36) but 2:1.02.167-1ubuntu1 is to be installed
              Depends: libefiboot1 (>= 37) but 37-2ubuntu2.2 is to be installed
              Depends: libefivar1 (>= 37) but 37-2ubuntu2.2 is to be installed
              Depends: liblzma5 (>= 5.1.1alpha+20120614) but 5.2.4-1ubuntu1 is to be installed
This error could be caused by required additional software packages which are missing or not installable. Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time.
Transaction failed: Package dependencies cannot be resolved
 The following packages have unmet dependencies:

grub-efi-amd64-signed: Depends: grub2-common (>= 2.02~beta2-36ubuntu3.31) but 2.04-1ubuntu26.12 is to be installed
grub2-common: Depends: grub-common (= 2.04-1ubuntu26.12) but 2.04-1ubuntu26.12 is to be installed
              Depends: libc6 (>= 2.28) but 2.31-0ubuntu9.2 is to be installed
              Depends: libdevmapper1.02.1 (>= 2:1.02.36) but 2:1.02.167-1ubuntu1 is to be installed
              Depends: libefiboot1 (>= 37) but 37-2ubuntu2.2 is to be installed
              Depends: libefivar1 (>= 37) but 37-2ubuntu2.2 is to be installed
              Depends: liblzma5 (>= 5.1.1alpha+20120614) but 5.2.4-1ubuntu1 is to be installed
This error could be caused by required additional software packages which are missing or not installable. Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time.
Transaction failed: Package dependencies cannot be resolved
 The following packages have unmet dependencies:

grub-efi-amd64-signed: Depends: grub2-common (>= 2.02~beta2-36ubuntu3.31) but 2.04-1ubuntu26.12 is to be installed
grub2-common: Depends: grub-common (= 2.04-1ubuntu26.12) but 2.04-1ubuntu26.12 is to be installed
              Depends: libc6 (>= 2.28) but 2.31-0ubuntu9.2 is to be installed
              Depends: libdevmapper1.02.1 (>= 2:1.02.36) but 2:1.02.167-1ubuntu1 is to be installed
              Depends: libefiboot1 (>= 37) but 37-2ubuntu2.2 is to be installed
              Depends: libefivar1 (>= 37) but 37-2ubuntu2.2 is to be installed
              Depends: liblzma5 (>= 5.1.1alpha+20120614) but 5.2.4-1ubuntu1 is to be installed
I checked on another computer with the same LTS version, this one kept up to date by running updates at least once every other day or every time the system demands it.
I have all the very same libraries with the very same versions but the grub-efi-amd64-signed is version 1.167.2+2.04-1ubuntu44.2 which won't install on the offending machine.
So how could I install the 3 packets ( grub-efi-amd64-signed, grub-common, grub2-common) without breaking anything or fixing the error ?
Many thanks in advance for your help and answer !
Have a nice day and stay safe !