How To Fix WL020 - Class & cannot be instantiated or interface & is not supported

SAP Error Message - Details

• Message type: E = Error

• Message class: WL - Workflow: run-time messages

• Message number: 020

• Message text: Class & cannot be instantiated or interface & is not supported

What causes this issue?

Could not create instance of class &V1& dynamically, or the class does
not support interface &V2&.

System Response

Processing is aborted.

How to fix this error?

Check class &V1&. This class must implement interface &V2&.

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 WL020 - Class & cannot be instantiated or interface & is not supported ?

  The SAP error message:
  WL020 Class & cannot be instantiated or interface & is not supported
  typically occurs in the context of SAP Web Dynpro or related ABAP Object-Oriented programming environments.
  
  Cause
  This error indicates that the system is trying to instantiate a class or use an interface that:
  
  Cannot be instantiated because it is an abstract class or an interface.
  Is not supported in the current context or environment.
  The class or interface might be missing, inactive, or not properly implemented.
  There could be a mismatch in the expected interface or class version.
  The class or interface might be not released or not available in the current system/client.
  Sometimes, this error can occur if the class is not generated properly or the runtime environment does not support the interface.
  
  
  Typical Scenarios
  
  Trying to instantiate an interface (which is not allowed).
  Trying to instantiate an abstract class.
  Using a class/interface that is not supported in the Web Dynpro runtime.
  Missing or inactive class/interface in the system.
  Version incompatibility after transport or upgrade.
  Incorrect usage of factory methods or class constructors.
  
  
  Solution
  
  
  Check the Class/Interface Definition:
  
  Verify if the class is abstract or if the object is an interface.
  Interfaces cannot be instantiated directly; you must instantiate a concrete class that implements the interface.
  
  
  
  Use the Correct Implementation Class:
  
  If you have an interface, instantiate a class that implements this interface.
  For example, instead of CREATE OBJECT <interface>, use CREATE OBJECT <concrete_class>.
  
  
  
  Check Activation and Existence:
  
  Ensure the class and interface are active in the system (use SE24 or SE80).
  If missing, import or activate the relevant development objects.
  
  
  
  Check for System or Component Support:
  
  Verify that the class/interface is supported in your SAP system version.
  Some classes/interfaces are only available in certain SAP releases or components.
  
  
  
  Review the Code:
  
  Look for incorrect instantiation code.
  Use factory methods if provided instead of direct instantiation.
  
  
  
  Check for Transport or Upgrade Issues:
  
  If this error appeared after a transport or system upgrade, verify that all related objects were transported and activated properly.
  
  
  
  Debugging:
  
  Use the debugger to check exactly where the instantiation fails.
  Check the runtime type and the parameters used.
  
  
  
  
  Related Information
  
  Transaction SE24: Class Builder to check class/interface properties.
  Transaction SE80: Object Navigator to browse and activate objects.
  SAP Notes: Search for SAP Notes related to WL020 for specific patches or known issues.
  Web Dynpro Documentation: For understanding supported classes/interfaces.
  ABAP OO Concepts: Abstract classes and interfaces cannot be instantiated directly.
  Factory Design Pattern: Often used to instantiate objects when interfaces are involved.
  
  
  Summary
  
  
  
  Aspect
  Details
  
  
  
  
  Cause
  Attempt to instantiate an abstract class or interface; unsupported class/interface used.
  
  
  Solution
  Instantiate a concrete class implementing the interface; ensure objects are active and supported.
  
  
  Check
  Class/interface activation, system support, correct usage in code, and transport status.
  
  
  
  
  If you provide the exact class and interface names (the placeholders & in the message), I can help you with more specific guidance.