Hi It seems that beast still does not work with gcc 9.3 and -fconcepts. If I try to build the beast test programs using -fconcepts, I still get a lot of errors such as those below. I thought this was fixed in 1.73. ???? Thanks --------------------- In file included from ../../../boost/beast/core/basic_stream.hpp:1457, from ../../../boost/beast/core.hpp:16, from doc/core_snippets.cpp:19: ../../../boost/beast/core/impl/basic_stream.hpp:781:1: error: no declaration matches ‘auto boost::beast::basic_stream< <template-parameter-1-1>, <template-parameter-1-2>, <template-parameter-1-3> >::async_connect(const endpoint_type&, ConnectHandler&&)’ 781 | basic_stream<Protocol, Executor, RatePolicy>:: | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from ../../../boost/beast/core.hpp:16, from doc/core_snippets.cpp:19: ../../../boost/beast/core/basic_stream.hpp:1202:5: note: candidates are: ‘template<class Protocol, class Executor, class RatePolicy> template<class Iterator, class ConnectCondition, class IteratorConnectHandler> requires completion_token_for<IteratorConnectHandler, void()> typename boost::asio::async_result<typename std::decay<RangeConnectHandler>::type, void(boost::system::error_code, Iterator)>::return_type boost::beast::basic_stream< <template-parameter-1-1>, <template-parameter-1-2>, <template-parameter-1-3> >::async_connect(Iterator, Iterator, ConnectCondition, IteratorConnectHandler&&)’ 1202 | async_connect( | ^~~~~~~~~~~~~ ../../../boost/beast/core/basic_stream.hpp:1141:5: note: ‘template<class Protocol, class Executor, class RatePolicy> template<class Iterator, class IteratorConnectHandler> requires completion_token_for<IteratorConnectHandler, void()> typename boost::asio::async_result<typename std::decay<RangeConnectHandler>::type, void(boost::system::error_code, Iterator)>::return_type boost::beast::basic_stream< <template-parameter-1-1>, <template-parameter-1-2>, <template-parameter-1-3> >::async_connect(Iterator, Iterator, IteratorCon