Message type: E = Error
Message class:  FKKBIX - Conv.Inv.: Billing (Invoice Preprocessing) 
Message number: 785
Message text: Bus. partner &1 and contract account &2 are not assigned to each other
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The SAP error message FKKBIX785 indicates that there is a mismatch or lack of assignment between a business partner and a contract account in the SAP system. This error typically occurs in the context of financial transactions, particularly in the areas of contract accounts receivable and payable (FI-CA).
Cause: The error arises when: The business partner (BP) is not linked to the specified contract account (CA). The contract account is not properly configured to recognize the business partner. There may be missing or incorrect data in the configuration settings for either the business partner or the contract account. The business partner might not be assigned to the correct role that is required for the contract account.
Solution: To resolve this error, you can follow these steps: Check Business Partner Assignment: Go to the transaction code BP (Business Partner) in SAP. Search for the business partner in question and check the roles assigned to it. Ensure that the business partner is assigned to
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