3248190 - Items of type XXX must not be edited in this tenant | 3-System Landscape - SAP S/4HANA Cloud Public Edition

When trying to access a Key User Extensibility app in a 3-System Landscape, one of the error messages below displays:

• Items of type XXX must not be edited in this tenant.
• Extensibility is not active. Use the Customizing Tenant instead.

SAP S/4HANA Cloud Public Edition

One possible reason is using the wrong tenant. There are two tenants in Development System:

• Customizing Tenant: Used for Business Configuration and Key User Extensibility.
• Development Tenant: Used for Developer Extensibility

Use the Development Tenant for Key User Extensibility and this is not allowed.

OR

The other possible reason is extensibility is not active in system yet.

In the SAP S/4HANA Cloud Public Edition, cloud starter edition or sales demo partner, extensibility for key users is deactivated by default.
Extensibility for key users can be activated.

Use the Customizing Tenant instead.

If the "Add"/"New" button is greyed out in Customizing Tenant, it means that it's necessary to activate the extensibility in this system. To activate the extensibility, please follow the steps below:

1. Go to "Extensibility Settings" app
2. Click on the "Key User Extensibility" button to set it to "ON" 

OR 

If  the right tenant is used, it's necessary to activate the extensibility. Activate it by opening the Fiori application Extensibility Settings and follow the activation process.

KBA 2283716 - Key User Application is not configured 

SAP Help Portal - Extensibility Settings

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