v14 Premium to v18.2 Premium upgrade, in PO Entry unable to select any PO's to load to screen, error 12 Files does not exist or already exists, Program SY_SalesTaxCalculaiton_bus.pvc, line 1970. Last file name varies depending on the PO# but seeing SY_Module and AP_Vendor. We don't have any problems in Vendor Maint, can open see all Tax Class, Tax Schedules and Tax Codes. Does anyone have any ideas how to resolve this?