Comment 32 for bug 1819915

Ok so after running the right command to install the older kernel:

apt-get install linux-image-4.15.0-44-generic linux-headers-4.15.0-44 linux-headers-4.15.0-44-generic linux-modules-extra-4.15.0-44

Also tested with -42 and -43 versions, Hibernation worked just like before with 4.15.0-43. So We can state this is a kernel bug since kernel 4.15.0-44, since with the -46, -45, -44 versions it doesn't work. It also worked on the -42 version.