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Avalara Help Center

Why does closing Statistics give the error "Invalid function call. Function reserved for external tax engines only."?

Overview

When closing the statistics window for invoices in Dynamics NAV the following error appears:

Invalid function call. Function reserved for external tax engines only. 
Page Edit - Sales Order Statistics must close. 

Environment

Dynamics NAV

Resolution

  • The “Use external Tax engine” box for the Tax Area code.(AvaTax) is checked. We recommend you not check the "Use external Tax engine" check-box for the Tax Area code (AvaTax).