This is a bugfix release.


  • Fix build failure when using WITH_ADNS=yes
  • Ensure that an error occurs if per_listener_settings true is given after other security options. Closes #1149.
  • Fix include_dir not sorting config files before loading. This was partially fixed in 1.5 previously.
  • Improve documentation around the include_dir option. Closes #1154.
  • Fix case where old unreferenced msg_store messages were being saved to the persistence file, bloating its size unnecessarily. Closes #389.


  • Fix mosquitto_topic_matches_sub() not returning MOSQ_ERR_INVAL for invalid subscriptions like topic/#abc. This only affects the return value, not the match/no match result, which was already correct.


  • Don't require C99 compiler.
  • Add rewritten build test script and remove some build warnings.