Message type: E = Error
Message class:  COM_PARTNER - Partner Processing Messages 
Message number: 559
Message text: Only one partner function of function category &1 is allowed
Only one partner function of function category &V1& can be used in the
object &V2&.
&SYSTEM_RESPONSES&
If the function category &V2& is used several times in a partner
determination procedure, the danger exists that the system, when
processing a process, cannot distinguish which partner functions should
be used to generate a specific partner, as there are several
possibilities for this. For example, two partner functions with function
category "ship-to party" can cause the system to decide on a partner
function without determining, but the user would have presumed the other
partner function to be the correct ship-to party.
Remove the partner function &V3& or every other partner function for the
function category &V1&.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message COM_PARTNER559 indicates that there is an issue with the partner functions in a particular business transaction or document. Specifically, it states that only one partner function of a certain function category is allowed. This typically occurs in scenarios where multiple partner functions of the same category are being assigned, which is not permitted by the system configuration.
Cause: The error is usually caused by: Duplicate Partner Functions: You may have assigned more than one partner function of the same category (e.g., multiple sold-to parties, multiple ship-to parties) in a document or transaction. Configuration Settings: The configuration in the partner function settings may restrict the assignment of multiple partners of the same function category. Data Entry Errors: Incorrect data entry or selection of partner functions during the creation or modification of a document.
Solution: To resolve the error, you can take the following steps: Check Partner Functions: Review the partner functions assigned to the document or
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