Notes I took as I upgraded two computers (one each running openSUSE 42.1 and 42.2) to 42.3.
Download via BitTorrent the DVD/USB Stick of the desired version. Verify the download’s integrity. Download SUSE Studio Image Writer (`sudo zypper install imagewriter`) and use it to write the installer to a USB stick.
Confirm the computer’s current OS is up to date. Run YaST – Software – Online Update.
Review your current repositories (YaST – Software – Software Repositories) for unneeded repositories. Investigate, disable, or delete as appropriate. Make note of any repositories that you will want to recreate later.
Run `sudo rpmconfigcheck` to catch any unresolved configuration files from previous upgrades. Address as needed. Meld is a good tool for doing this.
Read the new version’s release notes with an eye to anything that might be a problem with your hardware or preferred software.
Generate a list of installed packages with `rpm -qa > installed_packages.txt` for later reference. Even better would be to also maintain a list of software you commonly install and remove for reference.
Confirm that your backup system has been doing its job and your files are backed up.
Run the installer. You will be given two choices: upgrade or install. The former requires less configuration afterward; the latter leaves you with a cleaner system. Oddly, both times I selected upgrade and both times I was told there was insufficient free space in the root partition. So I wound up using install both times. Although post-install setup took longer, I was pleased with the space recovered in the root partition and with the apparent performance improvement.
You will be given an opportunity to set up networking. The only thing you need to do is set the hostname. The rest is entirely optional. The installer will complain if you don’t set up a working network but that can be ignored as the installer works fine offline.
If you chose to install then you will be asked to select packages. I save time by selecting Custom and then the Xfce environment. There’s not much point in tediously selecting here every package you’ll want because many of them will need to be upgraded anyway.
At the end of the installer, remove the USB stick before the computer reboots or the installer will be run again.
If you connect via Wi-Fi, log in as a user and enter the Wi-Fi password, choosing to save it. Repeat for each user.
Review your repositories (YaST – Software – Software Repositories). Confirm all repositories are for the new version. Disable or delete as appropriate. One you’ll want to delete is the USB stick. Before you delete it though, note where on /dev it is (e.g. /dev/sdf). You will need this information later.
Update any packages from the old version that were not in the installer with `sudo zypper up`.
Assuming you have no more computers to upgrade, recover the USB stick for normal use. If you did not take note earlier where in /dev it is found (I told you you’d need it!) then use `lsblk`.
Set up your printer (e.g. mine) and print a test page.
Install and remove packages as desired.
Add any third party repositories you need.
Run YaST – Software – Online Update Configuration to set your desired update parameters, then run YaST – Software – Online Update to do the first update.
Run `sudo rcrpmconfigcheck` to locate stale configuration files. Address as needed.
If you forgot to set the hostname during installation, set one now.
Write a reminder to yourself to upgrade before this version’s lifetime ends. I usually give myself three months’ leeway.