Attribute R3_SA_ORG with value (abbr. of sales org) already assigned to O (object ID number)

Attribute R3_SA_ORG with value (abbr. of sales org) already assigned to O (object ID number)

Message no. 5AT123
Diagnosis:
The attribute R3_SA_ORG can only be used with a specified value once at any particular time.
The value (Abbr. of sales org) was already assigned to object O (Object Id number).
Solution:
Reason u get this error is because you are trying to assign sales org of ECC or R/3 to organization created in BP in CRM manually but while importing sales org data from ECC or R/3 Organization in CRM is automatically created which means you jus have to delete the organization assigned instead assign the org that is shown in error.