How To Fix MW139 - Only one source of supply (ext. supplier or DC) can be maintained

SAP Error Message - Details

• Message type: E = Error

• Message class: MW - Messages IS-R / Allocation Tables

• Message number: 139

• Message text: Only one source of supply (ext. supplier or DC) can be maintained

What causes this issue?

Only one external vendor or distribution center may be maintained
as the source of supply for the plant. If you maintain the external
vendor, a third-party order is assumed, which means that the
external vendor supplies this material directly to the plant.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message MW139 - Only one source of supply (ext. supplier or DC) can be maintained ?

  The SAP error message MW139 ("Only one source of supply (ext. supplier or DC) can be maintained") typically occurs in the context of material master data or procurement processes. This error indicates that there is a conflict in the configuration of the source of supply for a material, specifically when trying to maintain both an external supplier and a distribution center (DC) as sources of supply for the same material.
  Cause:
  
  Conflicting Source of Supply: The system is designed to allow only one source of supply for a material at a time. If you attempt to assign both an external supplier and a distribution center as sources of supply, the system will trigger this error.
  Material Master Configuration: The material master record may have been incorrectly set up, leading to conflicting entries.
  Purchasing Info Records: There may be existing purchasing info records that conflict with the new entries you are trying to create or modify.
  
  Solution:
  
  Review Source of Supply: Check the material master record to see if both an external supplier and a distribution center are defined. You will need to decide which one you want to keep as the source of supply.
  Delete or Modify Entries: If you find both sources of supply, you will need to either delete one of them or modify the existing entries to ensure that only one source is maintained.
  
  If you want to keep the external supplier, remove the distribution center from the source of supply.
  Conversely, if you want to keep the distribution center, remove the external supplier.
  
  
  Check Purchasing Info Records: Review any purchasing info records associated with the material to ensure they do not conflict with your intended source of supply.
  Consult Documentation: If you are unsure about the implications of changing the source of supply, consult your organization's SAP documentation or reach out to your SAP support team for guidance.
  
  Related Information:
  
  Material Master Data: Understanding how material master data is structured in SAP can help prevent this error in the future. Familiarize yourself with the relevant views (e.g., Basic Data, Purchasing, MRP).
  Purchasing Info Records: These records link materials to vendors and can affect how materials are procured. Ensure that they are correctly maintained.
  SAP Notes and Documentation: Check SAP Notes for any updates or specific guidance related to this error message. SAP's help documentation can also provide insights into best practices for managing sources of supply.
  
  By following these steps, you should be able to resolve the MW139 error and maintain a consistent source of supply for your materials in SAP.