A Database Error Occurred
Unable to connect to your database server using the provided settings.Filename: /var/www/html/third_party/MX/Loader.phpLine Number: 99
Then address/setup i get error:
The requested URL /setup/ was not found on this server.
Do you run InvoicePlane ina sub-directory?
If yes, please check this.
If not, this sounds as your webspace / server has mod_rewrite disabled.
Please check this guide on how to check and setup mod_rewrite.