You get the error message "Please enter a party with role Seller" in a Sales Order, although the party role 'Seller' was deactivated in the Fine-Tuning and is non-mandatory.
Reproducing the Issue
1. Go to workcenter: Sales
2. Go to View: Sales Orders
3. Open any sales order
The error message is for the Item Party. As per the configuration in "Item Involved Parties" the party "Seller" is marked as mandatory.
Item parties are copied from Involved parties at Sales Order Header level by default or else they can be maintained manually.
To solve this issue either uncheck the Mandatory flag for item Involved Party in the Business Configuration or maintain a seller party for the item.
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