No activation of CDS-entities for Enterprise Search

What causes this issue?

In every system, there are CDS-based Data Sources - at least those
defined by Enterprise Search. CDS-based Data Sources are always
available for search.
Here, the CDS-based Data Sources have not been activated - a situation
which must not occur.

System Response

Search is not possible for CDS-based Data Sources; if run in a pure
CDS-mode, search as a whole is not possible.

How to fix this error?

Run report ESH_CDSABAP_ACTIVATION with default parametrization.
Contact SAP if the problem persists, or if it occurs repeatedly.

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.