Hello, Someone reported a discrepancy in boost trac that needs to be investigated by folks on the superproject team. What is claimed is that the superproject tag for boost-1.55 contains commit id 8c395a888c2d77bdc91e956ef24a07c0c87cdd24 for uuid, however this commit id does not exist. The tag id in the boost/uuid repository points to commit 98cf8322aef86e6398dbac7f9cd6bf766621d645. I would have opened up a github issue on the superproject to track this and resolve it, however the "issues" section is not activated for the superproject. https://svn.boost.org/trac10/ticket/13071 Instructions given to reproduce the issue are as follows: git clone https://github.com/boostorg/boost.git cd boost git submodule init libs/uuid git checkout boost-1.55.0 git submodule update libs/uuid and the last step will fail with: fatal: reference is not a tree: 8c395a888c2d77bdc91e956ef24a07c0c87cdd24 Unable to checkout '8c395a888c2d77bdc91e956ef24a07c0c87cdd24' in submodule path 'libs/uuid' Thanks, Jim