Hi, the version 2 of Boost/Chrono/IO introduce a bug on time_point<system_clock,D> i/o. There is an specialization for time_point i/o that I failed to test as the test was commented. When I have uncommented the test I have see that this was not really checked never. I have needed to fix a lot of things in the specific code, but I don't reach to make it work yet. As the release date is close I would prefer to disable the specialization for release 1.52 and take the time to fix the errors for the next release. I have created two tickets on Trac. https://svn.boost.org/trac/boost/ticket/7546 - time_point<system_clock> output version 2 fails to compile https://svn.boost.org/trac/boost/ticket/7547 - time_point<system_clock> input version 2 fails to compile Here you can see some of the modifications that I have since yesterday. The commit I have done today disable the feature. Of course I will need to document the limitation. They are mark as showstoppers, but as the default chrono/io version is yet version 1 the user should not be blocked. Another possibility is to disable the new chrono/io version 2 as a whole. Could I count with the permission to merge the code to disable the feature (https://svn.boost.org/trac/boost/changeset/81045) once the regression tests are run? Thanks, Vicente