--- a/plugins/mod_s2s.lua	Sun Jul 11 12:37:51 2021 +0200
+++ b/plugins/mod_s2s.lua	Sun Jul 11 12:41:32 2021 +0200
@@ -553,6 +553,7 @@
 local function session_close(session, reason, remote_reason, bounce_reason)
 	local log = session.log or log;
 	if not session.conn then
+		log("debug", "Attempt to close without associated connection with reason %q", reason);
 		return
 	end