How To Fix WY123 - Customer & is already assigned to another supplier

SAP Error Message - Details

• Message type: E = Error

• Message class: WY - Supplier Master

• Message number: 123

• Message text: Customer & is already assigned to another supplier

What causes this issue?

You wanted to assign a customer to the vendor. However, this customer
is already assigned to another vendor. You cannot carry out the
function.

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?

Please enter a different customer.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message WY123 - Customer & is already assigned to another supplier ?

  SAP Error Message:
  
  WY123 Customer & is already assigned to another supplier
  
  Cause:
  This error occurs when you try to assign a customer master record to a supplier master record, but the customer is already linked or assigned to a different supplier in the system. In SAP, a customer can only be assigned to one supplier at a time in certain business contexts (e.g., in vendor-customer integration scenarios, or when using the Customer-Vendor Integration (CVI) in S/4HANA).
  
  Explanation:
  
  The system prevents duplicate or conflicting assignments to maintain data consistency.
  This typically happens during master data synchronization or when creating/updating business partner relationships.
  For example, in SAP S/4HANA, the Business Partner (BP) approach integrates customer and vendor data. If a customer is already linked to a supplier BP, trying to assign it again to another supplier BP triggers this error.
  
  
  Solution:
  
  
  Check Existing Assignments:
  
  Identify which supplier the customer is currently assigned to.
  Use transaction codes like BP (Business Partner) or XK03 (Display Vendor) and FD03 (Display Customer) to check master data.
  In BP transaction, check the relationships tab to see linked partners.
  
  
  
  Remove or Change Existing Assignment:
  
  If the current assignment is incorrect or obsolete, remove or update it before assigning the customer to a new supplier.
  This might involve deleting or changing the relationship in the Business Partner master.
  
  
  
  Use Correct Business Partner Roles:
  
  Ensure that the customer and supplier roles are correctly maintained in the BP master.
  Avoid duplicate or conflicting roles.
  
  
  
  Synchronize Master Data Properly:
  
  If using Customer-Vendor Integration (CVI), run the synchronization programs carefully.
  Use transaction CVI_MIGRATION or related tools to check and fix inconsistencies.
  
  
  
  Consult with Master Data Governance:
  
  If your organization has a master data governance process, follow the procedure to correct master data conflicts.
  
  
  
  
  Related Information:
  
  
  Transactions:
  
  BP – Business Partner maintenance
  XK03 – Display Vendor
  FD03 – Display Customer
  CVI_MIGRATION – Customer Vendor Integration migration and synchronization
  
  
  
  Notes and Documentation:
  
  SAP Note related to CVI conflicts and synchronization errors.
  SAP Help Portal on Business Partner and Customer-Vendor Integration.
  
  
  
  Business Partner Integration:
  
  In SAP S/4HANA, customers and vendors are managed as Business Partners with different roles.
  Proper role assignment and relationship management are crucial to avoid such errors.
  
  
  
  
  If you provide more context (e.g., transaction used, system version), I can help with more specific steps.