Mexico: CFDI errors
CFDI40178— RFC of receiver invalid. Check the customer record; spaces and lowercase break it.CFDI40104— tax regime mismatch with RFC. Customer needs the correct fiscal regime selected, not just RFC.CFDI40147— currency on invoice doesn't match country of receiver. Either switch entity or accept the FX adjustment.
Brazil: NF-e rejections
Most common: 539 (duplicate invoice number — your sequence drifted) and 233 (state registration not active). Sequence drift comes from manual NF-e issuance outside the platform.
Spain: Facturae signature errors
Usually the signature certificate expired or the key password contains characters the signer doesn't handle. Re-export the certificate, use an alphanumeric password, re-upload.