3291421 - Error 'Application can only be used in the Extensibility Development System' in Development System - Development tenant.

• Unable to open "Extensibility Inventory" app in Development tenant.
• Getting error 'Application can only be used in the Extensibility Development System' while trying to open 'Extensibility Inventory' app in Development System - Development tenant.

SAP S/4HANA Cloud Public Edition

Using the wrong tenant/system to access Key User Extensibility apps.

Try to use Development System - Customizing tenant to access the 'Extensibility Inventory' App.

Note : Key User Extensibility is only available in the Test/Quality System in 2-System Landscapes or in the Development System - Customizing tenant in 3-System Landscapes.  In the SAP S/4HANA system, cloud starter edition or sales demo partner, extensibility for key users is deactivated by default. Extensibility for key users can be activated.

You can activate extensibility by yourself. Open the Fiori application "Extensibility Settings" and follow the activation process.

2283716 - Key User Application is not configured

SAP Help Portal - Extensibility Settings

SAP Help Portal - Transport Management Summary

Extensibility Inventory | SAP Help Portal

3342103 - Key User Extensibility apps are not available or read only - SAP S/4HANA Cloud Public Edition - SAP for Me

Key User Extensibility, Extensibility Tiles Error , Extensibility inventory, extensibility settings, customizing tenant, Application can only be used in the Extensibility Development System , KBA , BC-SRV-APS-EXT-SL , Manage and Import Software Collections , Problem