How To Fix ACM056 - Keyfield &1 of entity &2 is of DCL-forbidden type: String/XString

SAP Error Message - Details

• Message type: E = Error

• Message class: ACM - Message-Class for all ACM functions/exceptions

• Message number: 056

• Message text: Keyfield &1 of entity &2 is of DCL-forbidden type: String/XString

What causes this issue?

A field of type "String" or "XString" was marked as KEY.
No DCL roles/rules can be created for entities which have key fields of
LOB types "String" or "XString".

System Response

The DCL cannot be activated/generated

How to fix this error?

Change the structure of the CDS entity, so that no key field has a LOB
type ("String" or "XString"), otherwise this CDS entity cannot be access
protected via a DCL role.

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.

Smart SAP Assistant

• What is the cause and solution for SAP error message ACM056 - Keyfield &1 of entity &2 is of DCL-forbidden type: String/XString ?

  The SAP error message ACM056 indicates that there is an issue with a key field in a data model entity that is of a type that is not allowed for Data Control Language (DCL) operations. Specifically, it mentions that the key field is of type String or XString, which are types that are forbidden for DCL operations in certain contexts.
  
  Cause:
  
  Key Field Type: The key field in the entity is defined as a String or XString. In SAP, certain operations, especially those related to authorization and data access control, require key fields to be of a type that can be used in DCL statements. String and XString types are not suitable for this purpose.
  Entity Definition: The entity might have been defined incorrectly in the data model, leading to the use of an unsupported key field type.
  
  
  Solution:
  
  Change Key Field Type: Modify the key field in the entity definition to use a supported