How To Fix PPEENG151 - &1 between &2 and &3 must be compatible with the class hierarchy

SAP Error Message - Details

• Message type: E = Error

• Message class: PPEENG - iPPE Engine Messages

• Message number: 151

• Message text: &1 between &2 and &3 must be compatible with the class hierarchy

What causes this issue?

You have tried to create a relationship between the iPPE objects &v2&
and &v3& of type &v1&. In the Customizing for this relationship type,
it specifies that the iPPE objects &v2& and &v3& must be assigned to
product classes that are compatible with each other.
If the class check for iPPE relationships is activated, the system
checks whether the subordinate iPPE object is assigned to the same
product class as the higher-level iPPE object, or to a more general
product class.
For example, you have the following class hierarchy:
Automobile
Compact Class Product Family
Compact Vehicle Make A
Compact Vehicle Make B
Within iPPE, iPPE objects may be used for the product class 'Make A' if
they have been defined for this product class or for a more general
product class (Compact Class Product Family or Automobile). However,
iPPE objects that have been defined for a subclass (Compact Vehicle
Make A or B) cannot be used on the level of the Compact Class Product
Family.

System Response

The system does not allow you to create iPPE relationships if they do
not correspond to the class hierarchy.

How to fix this error?

Within the structure, select iPPE objects for a product class only if
they are assigned to the same or to a more general product class.

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 PPEENG151 - &1 between &2 and &3 must be compatible with the class hierarchy ?

  The SAP error message PPEENG151 indicates that there is an issue with the compatibility of the class hierarchy in the context of a production planning or engineering change management scenario. This error typically arises when you are trying to assign or relate objects (like materials, classes, or characteristics) that do not conform to the expected class hierarchy.
  Cause:
  The error occurs when:
  
  Incompatible Class Types: The objects you are trying to relate or assign do not belong to compatible classes in the class hierarchy. For example, if you are trying to assign a characteristic from one class to an object of another class that does not inherit from it.
  Incorrect Class Assignment: The class or characteristics assigned to the object may not be correctly defined or may not match the expected structure.
  Hierarchy Issues: There may be issues with the way the class hierarchy is structured, such as missing links or incorrect parent-child relationships.
  
  Solution:
  To resolve the PPEENG151 error, you can take the following steps:
  
  
  Check Class Hierarchy:
  
  Review the class hierarchy in the SAP system to ensure that the classes and characteristics you are working with are correctly defined and compatible.
  Use transaction codes like CL02 (Change Class) or CL03 (Display Class) to inspect the class definitions.
  
  
  
  Verify Object Assignments:
  
  Ensure that the objects you are trying to relate or assign are compatible with the class hierarchy. This may involve checking the characteristics and their assigned values.
  Make sure that the characteristics you are using belong to the correct class and that the class is properly assigned to the object.
  
  
  
  Adjust Class Definitions:
  
  If necessary, modify the class definitions to ensure that they align with the intended use. This may involve adding or removing characteristics or changing the class structure.
  
  
  
  Consult Documentation:
  
  Refer to SAP documentation or help resources for guidance on class hierarchies and characteristics to ensure you are following best practices.
  
  
  
  Testing:
  
  After making changes, test the process again to see if the error persists. If it does, further investigation may be needed to identify any additional issues.
  
  
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message. SAP frequently updates its knowledge base with solutions for common problems.
  Transaction Codes: Familiarize yourself with relevant transaction codes such as CL01 (Create Class), CL02 (Change Class), and CL03 (Display Class) for managing class definitions.
  User Forums: Engage with SAP community forums or user groups where similar issues may have been discussed, and solutions shared.
  
  By following these steps, you should be able to identify and resolve the cause of the PPEENG151 error in your SAP system.