Extension Projects in BAS: Handling Legacy SAP Fiori Apps
September 13, 2025
Business Technology Platform | SAP | UI-SAPUI5-Fiori

Introduction

  • Modern SAP Fiori apps use asynchronous views and support Adaptation Projects in BAS.
  • Legacy apps built with synchronous views cannot be extended via Adaptation Projects.
  • Examples: F0773 (Clear Incoming Payments), older transactional Fiori apps.
  • BAS provides a fallback to Extension Project in such cases.

Why Legacy Apps Require Extension Projects

  • Synchronous views load all UI components at once → not compatible with UI5 flexibility used in Adaptation Projects.
  • Adaptation Project assumes declarative metadata-driven app structure (Fiori Elements / modern UI5).
  • Legacy apps may also have custom controller logic, making adaptation tools insufficient.

How BAS Handles It

  • When you start an Adaptation Project for a legacy app:
    1. BAS inspects the app metadata.
    2. Detects synchronous views.
    3. Prompts: “This app uses synchronous views. Do you want to create an Extension Project instead?”
  • Selecting Yes scaffolds a project similar to the old Web IDE Extension Project.

Creating an Extension Project for a Legacy App (Step-by-Step)

1. Start in BAS

  • Go to File → New Project from Template.
  • Select SAP Fiori → Adaptation Project.

2. Pick Your Target App

  • Choose your S/4HANA system destination.
  • Search for app F0773.

3. BAS Detection

  • BAS checks the app metadata.
  • Since F0773 uses synchronous views, it shows a dialog:
    “This app uses synchronous views. Adaptation Project is not supported. Would you like to create an Extension Project instead?”

4. Confirm Extension Project Creation

  • Click Yes → BAS scaffolds an Extension Project (similar to old Web IDE style).
  • Folder structure will include ext/ (for controllers, fragments, etc.).

4.1 If you get any error “The Extensibility Project generator plugin was not found in your dev space and it is required for this action. To proceed, please install the <SAPUI5 Layout Editor & Extensibility> extension.”

Try to use (Legacy) SAPUI5 Adaptaion Project template it does not throw that error if your dev space has the extensions “SAPUI5 Layout Editor & Extensibility” installed. I got the similar error while using the new SAPUI5 Adpatation Project template.

5. Extend the App

Please right click on “.extconfig.json” and select Create Extension to Open the Extension Wizard

  • Add your custom logic in ext/controller.
  • Add custom fragments/UI in ext/view or ext/fragments.
  • Adjust manifest.json to declare your extensions.

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