If you sent a "Credit Limit of Party". Invoice Voucher Form will not Accept if Limit Exceed. I am unable to find this code section where it checks. Requested Member to share this section of code
In Ledger create/Alter mode in configuration enable provide credit limits then you will see below option Error during voucher entry if limit exceeds
"DEFTDL:src\voucher\vchreport\vchreport.tdl"(1039): Control : PartyLimitMsg : (NOT $IsOptional) AND @@PartyLimitExceeded