--- a/plugins/muc/mod_muc.lua	Fri Aug 17 00:31:24 2018 +0200
+++ b/plugins/muc/mod_muc.lua	Fri Aug 17 08:12:58 2018 +0100
@@ -450,6 +450,9 @@
 			else
 				return;
 			end
+                elseif room == false then -- Error loading room
+                        origin.send(st.error_reply(stanza, "wait", "resource-constraint"));
+                        return true;
 		end
 		return room[method](room, origin, stanza);
 	end, -2)