Possibility of automatic numbering when uploading external invoices

Hello

Invoice number is a key field on external customer/supplier invoice. Therefore you cannot create an invoice without it.

I can recommend you 2 step solution

1. Go to external file template and add a function to assign an invoice number when there is no any. You can use IF_EMPTY function on INVOICE_NO. Parameter should be COLUMN_REF(INVOICE_NO),”XXX”. this will assign XXX as invoice number in case of invoice no is missing
2. Create a custom event based on external supplier invoice and modify invoice number with next auto number where invoice number is XXX. You can modify based on an invoice series or your own numbering. You must create a deferred call not to face mutating trigger issue. Visit @dsj blog for detailed explanation of deferred call creation.

Alternatively you can also use CURRENT_DATE_TIME function to assign invoice number when creating IF_EMPTY function. 
 

Hope this helps