diff --git a/AUTHORS b/AUTHORS
index 112b7f36..1c367ffd 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -98,4 +98,5 @@ that much better:
  * Chris Williams
  * Robert Kajic
  * Jacob Peddicord
- * Nils Hasenbanck
\ No newline at end of file
+ * Nils Hasenbanck
+ * mostlystatic
\ No newline at end of file
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 0c962cd1..8674e9ee 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -2,6 +2,12 @@
 Changelog
 =========
 
+Changes in 0.6.X
+================
+
+- updated replicasetconnection - pop port if exists
+- bug fix for unknown connection alias error message
+
 Changes in 0.6.3
 ================
 - Updated sessions for Django 1.4
diff --git a/mongoengine/connection.py b/mongoengine/connection.py
index 3efb7d30..9cf8264a 100644
--- a/mongoengine/connection.py
+++ b/mongoengine/connection.py
@@ -86,7 +86,7 @@ def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
 
     if alias not in _connections:
         if alias not in _connection_settings:
-            msg = 'Connection with alias "%s" has not been defined'
+            msg = 'Connection with alias "%s" has not been defined' % alias
             if alias == DEFAULT_CONNECTION_NAME:
                 msg = 'You have not defined a default connection'
             raise ConnectionError(msg)
@@ -105,11 +105,13 @@ def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
                 for slave_alias in conn_settings['slaves']:
                     slaves.append(get_connection(slave_alias))
                 conn_settings['slaves'] = slaves
-                conn_settings.pop('read_preference')
+                conn_settings.pop('read_preference', None)
 
         connection_class = Connection
         if 'replicaSet' in conn_settings:
             conn_settings['hosts_or_uri'] = conn_settings.pop('host', None)
+            # Discard port since it can't be used on ReplicaSetConnection
+            conn_settings.pop('port', None)
             connection_class = ReplicaSetConnection
         try:
             _connections[alias] = connection_class(**conn_settings)