Latest upstream release: 3.0.1 Current version/release in Fedora 28: msgpack-1.4.2-3.fc27 Release URL: https://github.com/msgpack/msgpack-c/releases/tag/cpp-3.0.1 They claim ABI compatibility with 1.4.2. The C++ library is a header-only wrapper around the C library and I think they support all previous versions.
msgpack-3.0.1-1.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-582a1b1c1c
msgpack-3.0.1-1.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-582a1b1c1c
msgpack-3.0.1-1.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.