How To Fix GS020 - A multi-set cannot contain a multi-set

SAP Error Message - Details

• Message type: E = Error

• Message class: GS - Sets

• Message number: 020

• Message text: A multi-set cannot contain a multi-set

What causes this issue?

You have tried to enter a multi-set in a multi-set. However, you can
only enter basic sets and single sets in a multi-set.

System Response

The system rejects the set.

How to fix this error?

Select a permitted set.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message GS020 - A multi-set cannot contain a multi-set ?

  The SAP error message GS020, which states "A multi-set cannot contain a multi-set," typically occurs in the context of ABAP programming when you are trying to create a multi-set (a collection of unique values) that contains another multi-set. In ABAP, a multi-set is a data structure that allows for the storage of multiple values, but it cannot contain another multi-set as an element.
  Cause:
  The error arises when you attempt to define a multi-set that includes another multi-set as one of its elements. This is not allowed in ABAP, as multi-sets are designed to hold simple data types or structures, but not other multi-sets.
  Solution:
  To resolve this error, you need to ensure that your multi-set only contains simple data types or structures, and not other multi-sets. Here are some steps you can take:
  
  
  Review Your Data Structure: Check the definition of the multi-set and ensure that it does not include another multi-set. If you need to store multiple sets of values, consider using a different data structure, such as a nested table or a standard table.
  
  
  Flatten the Structure: If you need to store complex data, consider flattening the structure. Instead of having a multi-set within a multi-set, you can create a single multi-set that holds all the necessary values.
  
  
  Use Alternative Data Types: If you need to maintain a relationship between sets of values, consider using a different data type, such as a structure or a table, that can accommodate the relationships without nesting multi-sets.
  
  
  Refactor Your Code: If your logic requires the use of multi-sets, refactor your code to avoid nesting. This may involve changing how you collect and store data.
  
  
  Related Information:
  
  ABAP Documentation: Refer to the official SAP ABAP documentation for more details on data types and structures.
  SAP Community: Engage with the SAP Community forums to see if others have encountered similar issues and how they resolved them.
  Debugging: Use the ABAP debugger to step through your code and identify where the multi-set is being incorrectly defined.
  
  By following these steps, you should be able to resolve the GS020 error and adjust your data structures accordingly.