To take effect in subsequent systems, changes need to be transported.

What causes this issue?

You need to transport extension items from one system landscape to
another with the Adaptation Transport Organizer (ATO) key user apps:
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
<ZH>Configure Software Packages </>and <ZH>Register Extensions for
Transport </>
ELSE.
IF &[SWITCH]S4H_DOCU_CLOUD& = 'X'.
<ZH>Export Software Collection</>
ENDIF.
ENDIF.

How to fix this error?

You are using Extensibility Apps for Key Users on the SAP Fiori
launchpad to extend applications and their UIs.
These extension items take effect only in the system in which they were
created. You can find an overview of all extension items in a system in
the Extensibility Inventory app. ATO apps are the entry point for
transporting extension items to other systems.
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
Extension items can be transported with the <ZH>Configure Software
Packages </>and <ZH>Register Extensions for Transport </>apps to be
productively available und usable.
For more information see:
https://help.sap.com->SAP S/4HANA->Enterprise Technology->SAP
Netweaver->General Functions for Key Users->SAP Fiori
Applications->Extensibility
ELSE.
IF &[SWITCH]S4H_DOCU_CLOUD& = 'X'.
To make the extension items available in other system, the items need to
be transported with the ATO infrastructure. You can export extension
items from one system with the Export Software Collection app and import
them into another system with the Import Collection app. You can find an
overview of all extension items in a system in the Extensibility
Inventory App.
ELSE.
To configure ATO see SAP Note 2283716 - <ZK>S/4HANA Key User Application
is not configured</> for more details.
ENDIF.
ENDIF.

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