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

MW139 - Overview

• 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