diff --git a/fbchat/_exception.py b/fbchat/_exception.py
index df99b88..76aa047 100644
--- a/fbchat/_exception.py
+++ b/fbchat/_exception.py
@@ -90,7 +90,7 @@ class InvalidParameters(ExternalError):
 class NotLoggedIn(ExternalError):
     """Raised by Facebook if the client has been logged out."""
 
-    code = attr.ib(1357001)
+    code = attr.ib()
 
 
 @attr.s(slots=True, auto_exc=True)
diff --git a/fbchat/_mqtt.py b/fbchat/_mqtt.py
index 762fced..0fddeb7 100644
--- a/fbchat/_mqtt.py
+++ b/fbchat/_mqtt.py
@@ -168,10 +168,10 @@ class Listener:
         (j,) = session._graphql_requests(
             _graphql.from_doc_id("1349387578499440", params)
         )
-        try:
-            return int(j["viewer"]["message_threads"]["sync_sequence_id"])
-        except (KeyError, ValueError) as e:
-            raise _exception.ParseError("Could not find sequence id", data=j) from e
+        sequence_id = j["viewer"]["message_threads"]["sync_sequence_id"]
+        if not sequence_id:
+            raise _exception.NotLoggedIn("Failed fetching sequence id")
+        return int(sequence_id)
 
     def _on_connect_handler(self, client, userdata, flags, rc):
         if rc == 21:
@@ -321,6 +321,8 @@ class Listener:
                 # This error is wrongly classified
                 # See https://github.com/eclipse/paho.mqtt.python/issues/340
                 log.warning("Connection error, retrying")
+            elif rc == paho.mqtt.client.MQTT_ERR_CONN_REFUSED:
+                raise _exception.NotLoggedIn("MQTT connection refused")
             else:
                 err = paho.mqtt.client.error_string(rc)
                 log.error("MQTT Error: %s", err)