A couple of days ago I released FatturaElettronica 4.0.6. It adds support for legacy windows-1252 encoding to both XML and P7M invoices, a long-standing annoyance that could previously be circumvented via external code.

windows-1252 encoding in Italian e-invoices has been a persistent headache — it's technically outside the FatturaPA spec (which mandates UTF-8), but it crops up often enough in real-world invoices from older or misconfigured billing systems that users kept running into it. The Invoicetronic stack has been updated accordingly.