This situation occurs mostly in two cases:
Your digital signature certificate requires a periodic update (approximately every 2 years). This is done automatically when you use it regularly. The certificate update process requires a valid subscription. If you do not use your digital signature in the 3 months prior to the update deadline, or if the update has failed during this period, your digital signature certificate has expired and is no longer functional. Note: Notarius sends 3 email notifications in the month prior to the update deadline.