How To Fix FDT_CORE029 - A class and an interface must be defined

SAP Error Message - Details

• Message type: E = Error

• Message class: FDT_CORE - Formula & Derivation Tool: Core

• Message number: 029

• Message text: A class and an interface must be defined

What causes this issue?

The signature of an BRFplus expression type is defined by an ABAP-OO
interface. The functionality is defined in an ABAP-OO class implementing
that interface. This class also needs to implement the interface
IF_FDT_EXPRESSION.
Optionally there can be further classes defined for an expression type.
These are a query class, a UI class and a data exchange class. For a
detailed description of the functionality provided by these classes,
refer to the BRFplus documentation. If one of the classes is set it
needs to implement a corresponding interface.
These are the following:
The query class needs to implement IF_FDT_OBJECT_QUERY
The UI class needs to implement IF_FDT_UI_DEFINITION
The data exchange class needs to implement IF_FDT_DATA_EXCHANGE_EXTERNAL

System Response

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

How to fix this error?

Specify a correct interface and correct classes for the expression type.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message FDT_CORE029 - A class and an interface must be defined ?

  The SAP error message FDT_CORE029 indicates that there is an issue with the definition of a class or an interface in the context of the SAP Fiori Development Toolkit (FDT). This error typically arises when the system expects a class or interface to be defined but cannot find it, which can occur in various scenarios, such as when developing custom applications or enhancements.
  
  Cause:
  
  Missing Class/Interface: The specified class or interface is not defined in the system.
  Incorrect Naming: There may be a typo or incorrect naming convention used when referencing the class or interface.
  Transport Issues: If the class or interface was recently transported from another system, it may not have been transported correctly.
  Authorization Issues: The user may not have the necessary authorizations to access the class or interface.
  Development Environment Issues: There may be inconsistencies in the development environment, such as missing dependencies or incorrect configurations.
  
  
  Solution:
  
  Check Definitions: Verify that the class or interface