How To Fix 37789 - Nested step loops are not allowed (step loop not created)

SAP Error Message - Details

• Message type: E = Error

• Message class: 37 - Screen Painter

• Message number: 789

• Message text: Nested step loops are not allowed (step loop not created)

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message 37789 - Nested step loops are not allowed (step loop not created) ?

  The SAP error message 37789, "Nested step loops are not allowed (step loop not created)," typically occurs when there is an attempt to create a nested step loop in an ABAP program. Step loops are used in SAP to display data in a structured format, allowing users to navigate through multiple levels of data. However, SAP does not allow step loops to be nested within one another.
  Cause:
  The error is caused by the following scenarios:
  
  Nested Step Loops: You are trying to create a step loop inside another step loop. This is not permitted in SAP.
  Incorrect Program Logic: The program logic may inadvertently lead to the creation of a nested step loop.
  Improper Use of Loop Statements: Using loop statements incorrectly in the ABAP code can lead to this error.
  
  Solution:
  To resolve this error, you can take the following steps:
  
  
  Review the Code: Check the ABAP code where the step loops are defined. Ensure that you are not trying to create a step loop inside another step loop.
  
  
  Use Alternative Structures: If you need to display hierarchical data, consider using alternative structures such as:
  
  ALV Grids: Use ALV (ABAP List Viewer) grids which can handle hierarchical data more effectively.
  Subscreens: If you need to display additional details, consider using subscreens instead of nested step loops.
  
  
  
  Refactor the Logic: If your logic requires displaying related data, refactor the code to separate the data display into different sections or screens rather than nesting them.
  
  
  Debugging: Use debugging tools to trace the execution of your program and identify where the nested step loop is being created.
  
  
  Related Information:
  
  
  Step Loop Syntax: Familiarize yourself with the correct syntax for defining step loops in ABAP. The basic structure is:
  LOOP AT itab INTO wa.
    ...
    CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'.
    ...
  ENDLOOP.
  
  
  Documentation: Refer to the SAP documentation for step loops and ALV grids for best practices and examples.
  
  
  SAP Notes: Check SAP Notes for any specific patches or updates related to this error message.
  
  
  By following these steps, you should be able to resolve the error and implement a solution that meets your requirements without violating the constraints of SAP's step loop functionality.