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 is defined in the system. You can do this by using transaction SE80 (Object Navigator) or SE24 (Class Builder) to search for the class or interface.
  Correct Naming: Ensure that the name used in your code matches exactly with the defined class or interface, including case sensitivity.
  Transport Check: If the class or interface was recently transported, check the transport logs to ensure it was transported successfully. You may need to re-transport it if there were issues.
  Authorization Check: Ensure that the user has the necessary authorizations to access the class or interface. You can check this in transaction SU53 or by consulting with your security team.
  Rebuild/Refresh: If you are working in a development environment, try to rebuild or refresh the project to ensure that all dependencies are correctly loaded.
  Debugging: If the issue persists, consider debugging the application to trace where the error is being triggered and gather more context about the failure.
  
  Related Information:
  
  SAP Notes: Check for any relevant SAP Notes that may address this specific error or provide additional troubleshooting steps.
  Documentation: Review the SAP Fiori Development Toolkit documentation for guidelines on defining classes and interfaces.
  Community Forums: Engage with the SAP Community or forums for insights from other developers who may have encountered similar issues.
  
  By following these steps, you should be able to identify and resolve the cause of the FDT_CORE029 error in your SAP environment.