How To Fix DT221 - Field & does not lie within customer namespace

SAP Error Message - Details

• Message type: E = Error

• Message class: DT - Table activation (incl. indexes)

• Message number: 221

• Message text: Field & does not lie within customer namespace

What causes this issue?

Fields of <DS:TX.KUNDEN-INCLUDE>customizing includes</> and
<DS:TX.DDDOK_APPEND_STRUKTUR>append structures</> should lie in the
customer namerange. You can then be sure that there will be no
conflicts with SAP field names in future Release upgrades.
The customer namerange for fields is YY and ZZ.

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?

If they are new fields or fields which are only used in structures, you
are recommended to change the field names and the reports which access
them.
The field name for fields of database tables cannot be changed without
the corresponding data being lost. It is only necessary to change the
field name if the same name is used by SAP.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message DT221 - Field & does not lie within customer namespace ?

  The SAP error message DT221, which states "Field & does not lie within customer namespace," typically occurs when you are trying to use a field that is not defined in the customer namespace. In SAP, the customer namespace is reserved for custom developments, and fields or objects that are not defined in this namespace cannot be modified or extended by customers.
  Cause:
  
  Field Definition: The field you are trying to use is part of the standard SAP namespace and is not intended for customer modifications.
  Namespace Confusion: You may be trying to access or modify a field that is not defined in the customer namespace, leading to this error.
  Development Objects: If you are working on a custom development (like a Z-program or Z-table), and you reference a standard field incorrectly, this error can occur.
  
  Solution:
  
  Check Field Definition: Verify the field you are trying to use. Ensure that it is either a custom field (defined in the customer namespace) or that you are using it correctly as per SAP standards.
  Use Customer Namespace: If you need to create a custom field, ensure that you define it in the customer namespace (typically starting with 'Z' or 'Y').
  Modify Code: If you are modifying existing code, ensure that you are not trying to change standard fields directly. Instead, create a custom field in the customer namespace and use that.
  Consult Documentation: Review SAP documentation or the data dictionary (SE11) to understand the field's properties and its namespace.
  Transport Requests: If this error occurs during a transport, ensure that the transport request is correctly set up and that all necessary objects are included.
  
  Related Information:
  
  Namespace: In SAP, the namespace is a way to differentiate between standard SAP objects and customer-specific objects. Standard objects are usually prefixed with letters that are not 'Z' or 'Y'.
  Data Dictionary (SE11): You can use transaction SE11 to check the definitions of fields and tables, including their namespaces.
  ABAP Development: If you are an ABAP developer, ensure that you follow best practices for naming conventions and object definitions to avoid namespace issues.
  
  If you continue to face issues, consider reaching out to your SAP Basis or development team for further assistance, as they may have more context on the specific implementation and customizations in your SAP environment.