One speculation is that you have an empty placeholder in one of your files, e.g., ${}.
If that's the case, you could try adding a mapping from the empty string to the empty string as a workaround, filter('src/main/webapp/').into(task.to_s).using( 'copyright' => COPYRIGHT, 'version' => VERSION_STRING, '' => '' # empty strings ).run Does that work? On Mon, May 7, 2012 at 10:12 AM, Oliver Kopp <kopp...@googlemail.com> wrote: > You mean the following fragment? > > # replace version information in webapp files > # tip from > > http://stackoverflow.com/questions/6938984/buildr-filter-web-xml-in-packaging-war > filter_webapp = file("target/webapp") do |task| > filter('src/main/webapp/').into(task.to_s).using( > 'copyright' => COPYRIGHT, > 'version' => VERSION_STRING > ).run > end >