Buildout FAQ This document is aimed to help people answering all kind of buildout-related problems. It is maintained by community only, i.e you! So don't hesitate to add your questions and/or your answers. Error: Buildout is unable to extract .xz files Traceback xyz: Unable to extract the package /tmp/buildout-vURVvw. Unknown format. While: Installing xyz. Error: Package extraction error Solution Please make sure you use the good version of hexagonit.recipe.download by using the stack/slapos.cfg stack, or by manually specifying it by copying its version from http://git.erp5.org/gitweb/slapos.git/blob/HEAD:/stack/slapos.cfg?js=1#l73.