openhabian: Openhab2 cannot start

After a fresh install it seems that openhab2 cannot start. Any ideas what this depends on?

[23:20:00] pi@openHABianPi:~$ sudo /etc/init.d/openhab2 status
● openhab2.service - openHAB 2 - empowering the smart home
   Loaded: loaded (/usr/lib/systemd/system/openhab2.service; enabled)
   Active: deactivating (stop) (Result: exit-code) since Tue 2017-01-03 23:20:11 CET; 1s ago
     Docs: http://docs.openhab.org
           https://community.openhab.org
  Process: 19122 ExecStart=/usr/share/openhab2/start.sh server (code=exited, status=254)
 Main PID: 19122 (code=exited, status=254);         : 19280 (karaf)
   CGroup: /system.slice/openhab2.service
           └─control
             ├─19280 /bin/bash /usr/share/openhab2/runtime/bin/karaf stop
             └─19433 /usr/lib/jvm/java-8-oracle/jre/bin/java -Dopenhab.home=/usr/share/openhab2 -Dopenhab.conf=/etc/openhab2 -Dopenhab.runtime=/usr/share/openhab2/runtime -Dopenhab.userdata=/va...

Jan 03 23:20:11 openHABianPi start.sh[19122]: at java.lang.Integer.parseInt(Integer.java:542)
Jan 03 23:20:11 openHABianPi start.sh[19122]: at java.lang.Integer.parseInt(Integer.java:615)
Jan 03 23:20:11 openHABianPi start.sh[19122]: at org.apache.karaf.main.ConfigProperties.<init>(ConfigProperties.java:208)
Jan 03 23:20:11 openHABianPi start.sh[19122]: at org.apache.karaf.main.Main.updateInstancePidAfterShutdown(Main.java:226)
Jan 03 23:20:11 openHABianPi start.sh[19122]: at org.apache.karaf.main.Main.main(Main.java:191)
Jan 03 23:20:11 openHABianPi systemd[1]: openhab2.service: main process exited, code=exited, status=254/n/a
Jan 03 23:20:12 openHABianPi stop[19280]: stop: Ignoring predefined value for KARAF_HOME
Jan 03 23:20:13 openHABianPi stop[19280]: Exception in thread "main" java.lang.NumberFormatException: null
Jan 03 23:20:13 openHABianPi stop[19280]: at java.lang.Integer.parseInt(Integer.java:542)
Jan 03 23:20:13 openHABianPi stop[19280]: at java.lang.Integer.parseInt(Integer.java:615)
Jan 03 23:20:13 openHABianPi stop[19280]: at org.apache.karaf.main.ConfigProperties.<init>(ConfigProperties.java:208)
Jan 03 23:20:13 openHABianPi stop[19280]: at org.apache.karaf.main.Stop.main(Stop.java:42)