This blog explains about an overview of how to do the upgrade from SAP S/4HANA On-Premise 1709 (all feature package stacks) to SAP S/4HANA 1809. As a prerequisite for this upgrade, the HANA database must be upgraded to HANA 2.0 SPS03 or higher. For information on SAP HANA revision strategy, and SAP HANA Maintenance, please refer SAP Notes 2021789 & 2378962 - SAP HANA Revision and Maintenance Strategy (1.0 & 2.0) along with Product Availability Matrix (PAM).
Please check the following link for complete S/4HANA 1809 on-premise upgrade document (Includes both Back-End & Front-End Systems).
Overview of the upgrade process
The overview of the upgrade process shown in the figure below (including the tools, the phases, and the activities involved in the upgrade process) is intended to help you to plan and perform the upgrade from lower SAP S/
4HANA releases to SAP S/4HANA 1809.
Recommendation is that you have to do the activities in the sequence shown in below figure.
Simplification Item Catalog
To enable you to do an optimal planning of your upgrade to SAP S/4HANA 1809, SAP provided the simplification Item Catalog. The simplification Item Catalog is a tool that allows you to search or browse the complete collection of simplification items grouped by product version and presented by application or functional area. Each simplification item details and the steps that need to be taken for the conversion and/or the upgrade from a business and a technical point of view, both preparatory and follow-on steps and each item is available as a SAP Note. You need to search for the upgrade-relevant simplification items - most of the simplification items are not relevant for the upgrade. You will find the details here : https://launchpad.support.sap.com/#/sic/
a. System Requirements
b. Maintenance Planner
c. Simplification Item-Check
d. Custom Code Migration
e. Application-Specific preparation activities
2. Realize Phase
After you have done the steps of the prepare phase, you continue with the activities of the realize phase:
a. Software Update Manager (SUM)
b. Application-Specific follow-on activities