This file is a historic note, applicable only to dist.apache.org and not the archive. Original text as below: The Python bindings for proton-c are published at PyPi, and in order to allow a seemless install, a system was added such that if the relevant proton-c version couldnt be located on the system already then the setup would implicitly compile and install a local version for use. Unfortunately, when this functionality was added in earlier releases, reference was made to http://www.apache.org/dist/qpid/proton/ to download the matching release archive for installation. When these older releases are removed from there, it will break things for projects using the bindings from PyPi (or elsewhere) in their existing release versions should they actually be relying on the implicit proton-c install functionality. The 0.15.0 package at PyPi instead gets the files via the GitHub mirror for the source repo, rather than the apache.org/dist site. This issue was addressed in proton-0.16.0 via https://issues.apache.org/jira/browse/PROTON-1330, to distribute the needed C files within the generated python binding source bundle. The intention is to clear out the older releases over time, as other projects use of them phases out, and hopefully avoid/minimise significant disruption to other projects and end users.