00003: File too large for the channel
What it means
SdI code 00003 means the file is larger than the transmission channel you used accepts.
The usual cause
Each channel has its own limit in the SdI technical specifications: 5 megabytes per file for the web upload and the SDICoop web service, and 30 megabytes for a whole PEC message with its attachments. Check for large attachments embedded in the invoice.
How to fix it
Reduce the file, for example by compressing or removing large attachments, or split the invoices into several files, then send them again.
The code as published
Read the official document . Source: Elenco dei controlli effettuati sul file fattura del Sistema di Interscambio, version 2.0, published by Agenzia delle Entrate, fatturapa.gov.it, read on 8 November 2026.
Klarbon explains each code in its own words; the official wording is in the document linked above.