diff --git a/reference/mongo/mongoconnectionexception.xml b/reference/mongo/mongoconnectionexception.xml
index 5a09910cef..0d3447dfe2 100644
--- a/reference/mongo/mongoconnectionexception.xml
+++ b/reference/mongo/mongoconnectionexception.xml
@@ -70,6 +70,16 @@
       "server" instead of "$server".
      </para>
     </listitem>
+    <listitem>
+     <para>
+      <literal>Invalid Argument</literal>
+     </para>
+     <para>
+      This can be caused by attempting to connect to a machine that is up but
+      that the database isn't actually running on.  Make sure that you've
+      started the database server before connecting.      
+     </para>
+    </listitem>
     <listitem>
      <para>
       <literal>Permission denied</literal>