Restore backup from 3.3.1 into new appliance 5.4.1

i have been using ciphermail for a while and now i want to do some reworking.
I use ciphermail 3.3.1 an have a lot of users an certificates in that version. I created a backup with that old machine.

The import of that backup on the new installed virtual appliance seems to run without errors. Only the hint to reboot comes up. After reboot i can login into the machine, but there are no users, certificates domains. Only the configuration of the mta seems to be imported.

Is there a way to import old backups?

Thx Wolfgang

The database used by the Virtual Appliance changed from Postgres to MariaDB in version 4.1.0

See Email Encryption Gateway release notes - CipherMail Email Encryption

The CipherMail Gateway virtual appliance is now based on CentOS 7 instead of Ubuntu and runs MariaDB instead of PostgreSQL. Unfortunately this means that backups of previous virtual appliances cannot be imported directly in CipherMail Gateway 4.1.0+. Users with a support contract can contact us for help with migrating the database to the new version. Note: this change only impacts customers who wish to upgrade to the new CentOS-based virtual appliance.

One option is to export all certificates, as a p7b file, and then import them into the new appliance.