I'm planning the actions to execute during the migration to S/4 HANA on-premise from the custom code point of view. So far the Central ATC is setup to validate the current SAP ECC code where we can already implement most of the fixes in the ABAP code before the migration.
The next step is the Basis team proceeding with the system upgrade using SUM. They tell me I have to implement the rest of adjustments and fixes in SPAU, but to my knowledge SPAU is only used to adjust standard SAP objects that were modified with an "access key" and have changed during the upgrade.
I did SPAU before for smaller upgrades and that was the case, of course the Data Model was not changed and standard objects were not deprecated like in the S/4 HANA upgrade.
Then there is SPAU_EHN for the custom enhancements that could be impacted by the changes in the standard objects during the upgrade.
But when it comes to the rest of ABAP objects, let's say a totally independent custom program, an Z function module, custom classes, etc. Are the adjustments to these objects part of SPAU or, as I think, are they already part of the manual activities to execute after the upgrade is completed?
My idea about the order to adjust the custom objects is the following:
- Adjust everything possible in the current ECC with ATC validations
- [BASIS] Upgrade system with SUM
- Adjust modified standard objects in SPAU if necessary
- Adjust enhancements in SPAU_ENH if necessary
- COMPLETE UPGRADE PROCESS
- Adjust the rest of custom repository objects using Fiori Migration App, Quick Fixes and so on till the list is down to zero.
Following this order, I would use 1 Transport Request for the steps 3 and 4, and then as many as necessary for step 6.