During upgrade with target release ECC 6.0 (incl. enhancement packages) choose the option "KEEP" or "KEEP (with vendor key)", if possible, to keep the PBS level. Request the necessary vendor key via a support request from the PBS hotline .
During the upgrade with target release S/4HANA, you need a so-called attribute change package instead of vendor keys. You can request it via a support request from the PBS hotline . Send a transport research for all affected PBS modules (transaction /PBS/UTIL_Z9CP) to the hotline to provide you the appropriate attribute change packages for your level.
After the upgrade, the PBS modules should be updated to the latest level. If another delivery for the PBS products is available for the target release, this has to be imported. The necessary delivery packages are provided in the download area via the Online Helpdesk or via the support request of the PBS Hotline.