How To Fix WL387 - Result of operation '& & &' cannot be of type '&'

SAP Error Message - Details

• Message type: E = Error

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

• Message number: 387

• Message text: Result of operation '& & &' cannot be of type '&'

What causes this issue?

The following abbreviations are used in the message:
'I': whole numbers (ABAP data type Int1, Int2, Int4)
'P': packed numbers with decimal places and +/- signs (Dec, Packed)
'N': character string with numerical values (Numc)
'C': character strings (Character)
'D': date
'T': time
'O' or 'o': objects from the Business Object Repository

How to fix this error?

Only use elements or expressions that can be linked with the required
operation, that is, define the operation only between compatiable ABAP
data types or between object types:
You can only calculate with numbers (types I, P). As well as the basic
arithmetical operations (+ - * /), DIV operations (whole number
division) and MOD operations (modulo) are supported.
With date/time, only the following operations are allowed:
'Date - Date' result: whole number
'Date - Number' result: date
'Time - Number' result: time
'Time - Time' result: whole number.
You can only compare numbers with numbers (type I, P, N), dates with
dates, times with times, character-based types (C, N) or objects the
same as each other (o).
The result of a calculation or an assignment must be compatible in type
with the operand(s) and must not lead to an overflow, that is, the
result element selected must be large enough.
Hexadecimal numbers (X, RAW) and floating point numbers (F, FLTP) are
not supported in container operations at present. If applicable, define
object methods to implement operations with these types in a program.
You can find more information in the ABAP editor online help under the
keywords 'Data' and 'Move'.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message WL387 - Result of operation '& & &' cannot be of type '&' ?

  The SAP error message WL387 indicates that there is a type mismatch in an operation within your ABAP code or configuration. Specifically, the message states that the result of an operation involving three operands (represented by & & &) cannot be of the specified type (&). This typically occurs when the data types of the operands do not align with the expected type for the operation being performed.
  Cause
  The error can arise from several scenarios, including:
  
  Type Mismatch: The operands involved in the operation are of incompatible types. For example, trying to perform arithmetic operations on character strings or trying to concatenate incompatible data types.
  Incorrect Data Type Declaration: The variables or fields used in the operation may not be declared with the correct data types.
  Function Module or Method Return Type: If you are calling a function module or method that returns a value, the return type may not match the expected type in your code.
  
  Solution
  To resolve the WL387 error, you can take the following steps:
  
  
  Check Data Types: Review the data types of all operands involved in the operation. Ensure that they are compatible with each other and with the expected result type.
  
  
  Type Conversion: If necessary, perform explicit type conversion using ABAP functions like CONVERT, CAST, or other relevant methods to ensure that the operands are of compatible types.
  
  
  Review Function Modules/Methods: If the error is related to a function module or method, check the documentation to confirm the expected return type and ensure that you are handling the return value correctly.
  
  
  Debugging: Use the ABAP debugger to step through the code and inspect the values and types of the variables at runtime. This can help identify where the type mismatch occurs.
  
  
  Consult Documentation: Refer to SAP documentation or community forums for additional insights on the specific operation you are trying to perform.
  
  
  Related Information
  
  ABAP Data Types: Familiarize yourself with the various data types in ABAP, such as CHAR, NUMC, INT, FLOAT, etc., and their compatibility.
  Type Conversion Functions: Learn about ABAP type conversion functions that can help in converting data types safely.
  SAP Notes: Check SAP Notes for any known issues or patches related to the error message WL387.
  
  By following these steps, you should be able to identify the cause of the error and implement a solution to resolve it.