Source: libffi Version: 3.4.2-4 The documented source URL ftp://sourceware.org/pub/libffi/ is not valid for the current version 3.4.2. Sourceware does not have any 3.4.x version. Please change the d/watch and d/copyright file to present the right source URL, which is most probably https://github.com/libffi/libffi/releases