Structure cannot be enhanced

What causes this issue?

You cannot enhance the structure. The enhancement function is not
available for this structure type.

System Response

You can only enhance the structure in edit mode.

How to fix this error?

Change the structure in edit mode.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.