It appears not clear to all Tumbleweed users the easiest/correct way to do a typical update (when using zypper).
The recommended* way is “zypper dup --no-allow-vendor-change”
Tip: you can add [alias dup=‘sudo zypper dup --no-allow-vendor-change’] to your aliases ie. ~/.bashrc
‘zypper up’ will not delete packages, you will eventually get an inconsistent system.
‘zypper dup’ alone (if you have extra repo’s enabled) will allow vendor switch (e.g. inconsistent codecs) and can break your apps.
*(conclusions of factory mailing-list discussion).