Most likely none. There seems to be some problem when updating from old installs.
Just write piaware to the sd-card as described by step 2 of the following page:
PiAware - build your own ADS-B ground station for integration with FlightAware - FlightAware
You might want to save your piaware-config.txt somewhere else before and also add your feeder-id.
For Beginners - How to Get Back Existing Station Number in A Fresh Install
Then when you have written the image use the piaware-config.txt you saved and put the sd-card back in the RPi.
Should all work fine.