In S/4HANA Conversion Projects (aka. Brownfield) one showstopper can be the uninstallation of Add-Ons. Often this causes trouble during SUM Procedure. There is a little section for this in the Convesion Guide (Chapter 3.5) – see https://help.sap.com/doc/2b87656c4eee4284a5eb8976c0fe88fc/1909.000/en-US/CONV_OP1909.pdf
In order to check this upfront and even simulate it, SAP developed a “Add-On Uninstallation Simulation Tool”. Introduced with SPAM Version 74 this Simulation Tool is available. With this Tool you can only simulate not delete Add-Ons!
All prerequisites are described here: https://help.sap.com/viewer/1057be4036894efeb69007cc3e0cb3c0/LATEST/en-US/95bcbcbdfe644ba3832a2d6e657e47c8.html
Transaction Code: SIM_UNINST
Choose your component and click “Simulate” and you can see the results.
Example: Add-On GBX01HR – Fiori X1 HCM
This is relatively easy and a corresponding SAP Notes is already linked with further information. All operations are already predefined and no further action is required.
Already simulated components are marked with a little flag in column “Simulation”. Click on the flag and see the results of your Simulation.
Example: Add-On UIAPFI70 – UI SFIN
This is a little more effort, because there is no predefined operation. Hence you have to simulate your selected operation. In edit mode you can select operation “ignore / delete” for each line.
Once done you can simulate. In the results your operation is considered (I chose “delete”). In this case it even gives you the proposed coding for a “Plugin Class” that needs to be created for deletion, which is very helpful.