What does the error message java.net.UnknownHostException mean?
For the operation of BL Banking an Internet connection is required. The error message UnknownHostException means that an Internet connection could not be established. First you could enter an URL in the browser to check if there is a general connection problem, which also occurs independent from the BL Banking client. Often a disruption of the Internet connection persists only short-time and disappears by itself.
See also chapter General - System requirements - Internet connection.
Furthermore you can enter the URL of the banking server in the browser to check if the server of the bank can be reached. You can look-up this URL in the bank properties by double-clicking the bank in the Jobs perspective. For most banking servers a description of the manufacturer is displayed in the browser.
See also chapter Jobs - Bank properties.
If this check was successful, but the connection still does not work in BL Banking, you should check if a proxy server is entered in the settings of the browser. If this is the case, you should also enter it in BL Banking. Additionally you can also check, if the proxy in the browser is configured via a so-called PAC file.
See also chapter General - Preferences - General information.