How To Fix FL389 - Only tables with flat line structure are allowed in RFC

SAP Error Message - Details

• Message type: E = Error

• Message class: FL - Function Builder messages

• Message number: 389

• Message text: Only tables with flat line structure are allowed in RFC

What causes this issue?

A structure with flat structure means that it contains only fields of
the data types ACCP, CHAR, CLNT, CUKY, CURR, DATS, DEC, FLTP, INT1,
INT2, INT4,LANG, NUMC, PREC, QUAN, RAW, TIMS, or UNIT.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message FL389 - Only tables with flat line structure are allowed in RFC ?

  The SAP error message FL389, which states "Only tables with flat line structure are allowed in RFC," typically occurs when you are trying to pass a table structure that is not flat (i.e., it contains nested structures or complex data types) to a Remote Function Call (RFC) in SAP. RFCs require that the data structures passed to them be flat, meaning they should not contain any nested tables or structures.
  Cause:
  
  Nested Structures: The table you are trying to pass contains nested structures or sub-tables.
  Complex Data Types: The data type of the table is not a simple flat structure, which is required for RFC calls.
  Incorrect Definition: The table may have been defined incorrectly in the ABAP Dictionary, leading to a non-flat structure.
  
  Solution:
  
  Flatten the Structure: Modify the table structure to ensure it is flat. This means removing any nested tables or structures and ensuring that all fields are at the same level.
  Use a Different Data Type: If you need to pass complex data, consider using a different approach, such as:
  
  Passing multiple flat tables instead of a single nested table.
  Using a structure that contains only simple data types.
  
  
  Check RFC Function Module: Ensure that the RFC function module you are calling is designed to accept the data structure you are passing. If it is not, you may need to create a new RFC function module that can handle the required data structure.
  Review ABAP Dictionary: Check the definitions in the ABAP Dictionary (SE11) to ensure that the table is defined correctly and does not contain any nested structures.
  
  Related Information:
  
  RFC (Remote Function Call): A communication interface in SAP that allows for the execution of functions in a remote system.
  Flat Structure: A data structure where all fields are at the same level, with no nested tables or structures.
  ABAP Dictionary (SE11): The tool used to define and manage database objects in SAP, including tables, views, and data elements.
  
  Additional Tips:
  
  If you are unsure about how to flatten a structure, consider consulting with an experienced ABAP developer or SAP consultant.
  Testing the changes in a development environment before moving to production is crucial to avoid disruptions.
  Review SAP documentation or community forums for specific examples and best practices related to RFC and data structures.