How To Fix CL537 - Class type "&" is different to valid class type "&"

CL537 - Overview

• Message type: E = Error

• Message class: CL - Classification

• Message number: 537

• Message text: Class type "&" is different to valid class type "&"

What causes this issue?

The class type of the first allocation record is compared with the
others. If the class types are different, the record is ignored.

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?

Error message extract from SAP system. Copyright SAP SE.

CL537 - Details

• The SAP error message CL537 indicates that there is a mismatch between the class type of the object you are trying to work with and the expected class type in the system. This typically occurs in the context of object-oriented programming in ABAP, particularly when dealing with class definitions and instantiations.
  
  Cause:
  
  Class Type Mismatch: The error arises when you attempt to use a class or object of a certain type that does not match the expected class type. For example, if you are trying to instantiate a class of type "ZCL_MY_CLASS" but the system expects a class of type "CL_MY_EXPECTED_CLASS", this error will occur.
  Inheritance Issues: If the class you are trying to use is not a subclass of the expected class type, this can also lead to this error.
  Incorrect Type Declaration: The variable or parameter may have been declared with the wrong class type, leading to a mismatch when the code