00101: Signing certificate revoked
What it means
SdI code 00101 means the certificate used to sign the file has been revoked.
The usual cause
Check the certificate's status with the certification authority.
How to fix it
Sign the file again with a valid certificate and send it under a new name.
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.