Comment # 9 on bug 1228415 from Michael Andres

(In reply to Paul Fee from comment #8)
> Should the same approach be used when upgrading across distro versions?  If
> starting from 15.4, should one upgrade to the 15.5 version of zypper before
> upgrading the rest of the packages?

Within the SLE15 family the zypp stack is not branched, i.e. we distribute the
same zypp version to all SPs until they reach their EOL (same for Leap).

If you don't wait far longer than the EOL of the old SP, the zypp version in
both SPs are (nearly) the same. So it's usually safe to fully update the old SP
and use the 'old' zypper to drive the dup. 

More important here is that all old repos are disabled and all the new repos
enabled when doing the dup. So you don't get a mixed system.


Big steps - as from SLE12 to SLE15 - are different. Here you can not be sure
that the SLE12 update stack fully understands and supports SLE15 systems and
repos. Here you want the new stack to drive the dup. That's why this is often
done offline, because bringing the SLE15 zypp stack into a SLE12 system may be
difficult.