diff -r 50f1c09541cd -r da92afa267cf plugins/mod_dialback.lua
--- a/plugins/mod_dialback.lua	Sun Nov 23 20:43:42 2008 +0100
+++ b/plugins/mod_dialback.lua	Sun Nov 23 20:44:48 2008 +0100
@@ -55,8 +55,12 @@
 				log("warn", "dialback for "..(origin.dialback_verifying.from_host or "(unknown)").." failed");
 				valid = "invalid";
 			end
-			origin.dialback_verifying.sends2s(format("<db:result from='%s' to='%s' id='%s' type='%s'>%s</db:result>",
-				attr.from, attr.to, attr.id, valid, origin.dialback_verifying.dialback_key));
+			if not origin.dialback_verifying.sends2s then
+				log("warn", "Incoming s2s session %s was closed in the meantime, so we can't notify it of the db result", tostring(origin.dialback_verifying):match("%w+$"));
+			else
+				origin.dialback_verifying.sends2s(format("<db:result from='%s' to='%s' id='%s' type='%s'>%s</db:result>",
+					attr.to, attr.from, attr.id, valid, origin.dialback_verifying.dialback_key));
+			end
 		end
 	end);