  Mobile operating systems evolve quickly, frequently updating the APIs that
app developers use to build their apps. Unfortunately, API updates do not
always guarantee backward compatibility, causing apps to not longer work
properly or even crash when running with an updated system. This paper presents
FILO, a tool that assists Android developers in resolving backward
compatibility issues introduced by API upgrades. FILO both suggests the method
that needs to be modified in the app in order to adapt the app to an upgraded
API, and reports key symptoms observed in the failed execution to facilitate
the fixing activity. Results obtained with the analysis of 12 actual upgrade
problems and the feedback produced by early tool adopters show that FILO can
practically support Android developers.FILO can be downloaded from
https://gitlab.com/learnERC/filo, and its video demonstration is available at
https://youtu.be/WDvkKj-wnlQ.
