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A private SnapPack version always takes higher precedence over the configured Org-level SnapPack.
Snaplex Versions and Snap Packs
During the five-week window for Snaplex auto-upgrade, Snaplex instances could be in one of three states.
All Snaplex instances are on Previous Platform version: Design-time snap catalog uses old snaps
Mixed Versioned Snaples instances include some Snaplex instances are on the previous Platform version and some are running on new: Design-time Snap Pack Catalog uses old snaps
All Snaplex instances on New platform version: Design-time snap catalog uses new snaps
So until all Snaplex instances are upgraded to the new version, the design-time Snap Pack Catalog will use the old Snap Pack Catalog. If one Snaplex is switched back to the previous Snaplex version after the upgrade, the catalog again reverts to the previous version.
However, the execution time Snap Pack Catalog does not have this behavior. Rather, new Snap Pack versions are used on new JCC nodes and the previous versioned Snaps are used on the old JCC nodes with the previous version.