At the moment InvoicePlane is not able to convert your FusionInvoice database on it’s own. But I’m aware of the problem and a guide how to move the database is on it’s way. Stay tuned!
The InvoicePlane Migrationtool has been released now and is available at GitHub repository.
You can use this tool to migrate the database from FusionInvoice v1.x to InvoicePlane. If you need any help please take a look at the wiki.