How To Fix R1451 - External BP number &1 has already been assigned for business partner &2

SAP Error Message - Details

• Message type: E = Error

• Message class: R1 - Business Partner Messages from S_BUPA_GENERAL

• Message number: 451

• Message text: External BP number &1 has already been assigned for business partner &2

What causes this issue?

A business partner was created with an external BP number that is
already being used for one or more business partners.

System Response

If you create a business partner in the <ZH>BP dialog</> with an
external BP number that is already being used, you can still save the
business partner's data.
In this case the system issues this message as a warning.
Note
The following information is not relevant if you are using a CRM system.
If you <ZH>create</> a business partner with an external BP number using
<ZH>Direct Input</> in an ERP System and the external BP number is
already being used for one or more business partners, the business
partner's data is still saved.
In these cases the system issues this message as a warning.
If you <ZH>change</> a business partner with an external BP number using
<ZH>Direct Input</> in an ERP System and the external BP number is
already being used for one or more business partners, this message is
issued as an error.
This is the case if the field business partner (BU_PARTNER) is not
filled, and the external BP number (BU_BPEXT) is referred to as an
identifying characteristic.
You must state the business partner number (BU_PARTNER) in order to
change the business partner in the Direct Input.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message R1451 - External BP number &1 has already been assigned for business partner &2 ?

  The SAP error message R1451 indicates that there is a conflict with the assignment of an external Business Partner (BP) number. Specifically, it means that the external BP number you are trying to assign to a business partner is already in use by another business partner in the system.
  
  Cause:
  
  Duplicate External BP Number: The external BP number you are trying to assign is already assigned to a different business partner.
  Data Migration Issues: If you are migrating data from another system or performing mass uploads, there may be duplicates in the data.
  Incorrect Configuration: The configuration settings for external number assignment may not be set up correctly, leading to conflicts.
  
  
  Solution:
  
  
  Check Existing Assignments: 
  
  Use transaction code BP to check the existing business partners and their assigned external numbers. Look for the external BP number in question to see which business partner it is currently assigned to.
  
  
  
  Change External BP Number: 
  
  If the external BP number