I had the following code, which worked in 1.58: #include #include #include /// @todo move elsewhere, because it will conflict with others' implementations of outputting vectors template<typename T> inline boost::log::formatting_ostream& operator<<(boost::log:: formatting_ostream& out, std::vector<T>& v) { out << "["; size_t last = v.size() - 1; for(size_t i = 0; i < v.size(); ++i) { out << v[i]; if (i != last) out << ", "; } out << "]"; return out; } I used it to output a std::vector<float> as follows: BOOST_LOG_TRIVIAL(trace) << “Real joint angles from FRI: " << realJointPosition << "\n"; However this now seems to fail in 1.59. I’ve created a github gist with the compiler output https://gist.github.com/ahundt/5869dbd09e889b7153c3 in case that’s helpful as well. I see that the update recently had some breaking changes, what is the new way to provide the desired functionality? Thanks for your help. Cheers! Andrew Hundt