
"CFOP Incoming" is a mandatory field
In the Tax Codes — Setup window, you have defined a tax code, and you have chosen the Update button. However, the CFOP Incoming field is empty.
The CFOP Incoming field is mandatory when at least one of the following tax categories is linked with tax types selected for the particular tax code:
PIS
IPI
COFINS
ICMS
In the CFOP Incoming field, specify a valid code.