How to solve dpkg-source source problem when building a package?

Avoid the Debian bureaucracy by just building the binary: dpkg-buildpackage -b

change the format in debian/source/format from 3.0 (quilt) to 3.0 (native) if you do not want to use quilt. This solved the problem for me anyway.

This means you have applied changes to the unpacked upstream source which are not part of a patch in the debian/patches/ directory, or listed in the series file in there if they are; and/or there is some inconsistency in the state of quilt's application of the patches.

Looking at the mentioned file in /tmp will show you the changes in question.