Message type: E = Error
Message class:  VK - Pflege und Bearbeitung von Konditionen 
Message number: 387
Message text: Condition type &1 does not allow supplementary conditions
Branching to the additional condition screen is only allowed for
conditions with a permitted condition type.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Check the Customizing setting for the condition type. The additional
pricing procedure for this condition type is not entered.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message VK387 indicates that a specific condition type does not allow supplementary conditions. This typically occurs in the context of pricing in sales and distribution (SD) or purchasing modules, where certain condition types are configured to not accept additional conditions or discounts.
Cause: Condition Type Configuration: The condition type in question (represented by &1 in the error message) is configured in such a way that it does not permit supplementary conditions. This could be due to settings in the condition type configuration in the SAP system. Pricing Procedure: The pricing procedure associated with the transaction may not allow supplementary conditions for the specified condition type. Master Data Issues: The master data (like customer or material master) may have settings that conflict with the use of supplementary conditions.
Solution: Check Condition Type Configuration: Go to the transaction code V/06 (for condition types) and check the configuration of the condition type that is causing the error. Look
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