I like my systems to the latest versions, the fact that 14.2 was release a long time makes it ever so much more to want to upgrade it.

According to the UPGRADE.txt the upgrade is as follows: Slackware 15.0 UPGRADE.txt

The upgrade in a nutt shells is:

 telinit 1 (brig the system to single user)

download the ISO

wget https://mirrors.slackware.com/slackware/slackware-iso/slackware64-15.0-iso/slackware64-15.0-install-dvd.iso

once it is done

mount -o loop <PATH to iso> /path/to/mnt/dir

note that each VPS are 20gig images so you can only install the main sets and skip the x,xp,kde,xfce

once that is mounted you will issue the following.

upgradepkg --install-new /mnt/point/a/aaa_glibc-solibs-*.txz
upgradepkg /mnt/point/slackware/a/pkgtools-*.txz
upgradepkg /mnt/point/slackware/a/tar-*.txz
upgradepkg /mnt/point/slackware/a/xz-*.txz
upgradepkg /mnt/point/slackware/a/findutils-*.

you are limited by space so remeber that you can only install the essentials

so you will cd to /mnt/path/slackware64 and then issue the following

upgradepkg --install-new --terse /mnt/point/slackware64/a/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/ap/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/d/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/e/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/f/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/k/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/l/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/n/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/t/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/tcl/*.t?z
upgradepkg --install-new --terse /mnt/point/slackware64/y/*.t?z

we skipped kde,x,xap,xfce

this should allow us to upgrade without any no space left on device errors.