How To Fix CNV257 - For domain &, data element & and convfunc &, source package is not unique

CNV257 - Overview

• Message type: E = Error

• Message class: CNV - Conversion: Messages for Conversion Services (CNCC)

• Message number: 257

• Message text: For domain &, data element & and convfunc &, source package is not unique

What causes this issue?

The combination
domain &V1&
data element &V2&
routine &V3&
occurs in more than one source package. This causes a conflict.

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?

Set field source package for the domain / data element manually.

Error message extract from SAP system. Copyright SAP SE.

CNV257 - Details

• The SAP error message CNV257 typically occurs during data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or other data migration tools. This error indicates that there is an issue with the uniqueness of the source package for a specific domain, data element, and conversion function.
  
  Cause:
  The error message "For domain &, data element &, and convfunc &, source package is not unique" suggests that the system has encountered multiple source packages that match the criteria defined for the specified domain, data element, and conversion function. This can happen due to:
  
  Duplicate Entries: There are multiple entries in the source data that correspond to the same domain and data element, leading to ambiguity in the conversion process.
  
  Configuration Issues: The configuration of the migration or conversion process may not be set up correctly, causing the system to misinterpret the source data.
  Data Model Changes: Changes in the data model or