Upgrade is a process by which a version of a TSS 14.x or 15.x repository server is made compatible with a later version of TSS 15.x; for example, upgrading a v14.3 repository server to be used with v15.3.
Trillium Software recommends that you upgrade existing repositories during the installation of TSS 15.x. However, if for some reason, you did not perform the upgrade, manually copying the source repository to the destination repository is not applicable. You will instead need to use the mtb_admin upgrade command for repository upgrade.
Repository upgrade is used to patch from version to version. It only adds new tables and does not remove or significantly alter existing tables.