Comment # 3 on bug 1198978 from Bryan Gartner

Already sent these steps to partner as well

- please check all of the repo files in /etc/zypp/repos.d/* and ensure that
there is not a text element of 15.2 in the URLs. If there is, please do the
Step 5 from the document (sed) to replace those and retry the dup

- also try a modified dup command to see if this addresses the issue

    zypper dup --releasever 15.3 --allow-vendor-change --dlownload-in-advance

And after they try/reply, will follow-up to get more details/logs if needed