Cannot update intel microcode using apt-get

Question

I'm using Debian Stretch, kernel 4.17.11 and when I run

sudo apt-get install intel-microcode

I get

Package intel-microcode is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source

Answer 1

You are not finding the package intel-microcode, because it is on the non-free repositories, that are not added by default on installation time.

You need to add it to your /etc/apt/sources.list

As in:

deb http://ftp.us.debian.org/debian/ stretch main contrib non-free 
deb http://security.debian.org/ stretch/updates main contrib non-free

Do not forget to run sudo apt update after adding the non-free repository and before running sudo apt install.

Package: intel-microcode (3.20180425.1~deb9u1) [non-free]

Processor microcode firmware for Intel CPUs

This package contains updated system processor microcode for Intel i686 and Intel X86-64 processors. Intel releases microcode updates to correct processor behavior as documented in the respective processor specification updates.

For AMD processors, please refer to the amd64-microcode package.