How To Fix W8060 - Table action "Append" is only possible for single-level expressions

W8060 - Overview

• Message type: E = Error

• Message class: W8 - Workflow: Expressions, data flow

• Message number: 060

• Message text: Table action "Append" is only possible for single-level expressions

What causes this issue?

The table action "Append" (Syntax '//') is only possible, if the
assignment is to a single-level expression.

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.

W8060 - Details

• Certainly! Here's a detailed explanation for the SAP error message:
  
  SAP Error Message:
  W8060 Table action "Append" is only possible for single-level expressions
  
  
  Cause:
  This warning occurs when you try to use the APPEND statement on a nested/internal table expression rather than on a single-level internal table variable.
  In ABAP, the APPEND statement is designed to add a line to a single-level internal table. If you attempt to append to a nested table or a complex expression (like a component of a structure that is itself a table), the system raises this warning.
  Example causing the error:
  TYPES: BEGIN OF ty_line,
           subtab TYPE TABLE OF string,
         END OF ty_line.
  
  DATA: itab TYPE TABLE OF ty_line,
        wa   TYPE ty_line.
  
  APPEND 'abc' TO wa-subtab.  " This is valid
  APPEND wa-subtab TO itab-subtab. " Invalid, causes W8060
  Or more commonly:
  APPEND wa-subtab TO