The directory structure of ASIO changed a bit and now the website pages of samples in old versions no longer direct to the correct page in the latest version: <https://www.boost.org/doc/libs/1_51_0/doc/html/boost_asio/example/icmp/ping.cpp> I wanted to see how to code a ping so I googled for "boost asio ping" and the top result was for 1.51.0. (I never get the latest code, but I can always jump to an older version and then jump from there to the latest. It just didn't work this time.) It did work for 1.67.0 (later in the google search results) which led to the current page: <https://www.boost.org/doc/libs/1_79_0/doc/html/boost_asio/example/cpp03/icmp/ping.cpp>