diff --git a/osu.Game/Online/RealtimeMultiplayer/IMultiplayerServer.cs b/osu.Game/Online/RealtimeMultiplayer/IMultiplayerServer.cs
index eb9eddbdf5..565c07d0ec 100644
--- a/osu.Game/Online/RealtimeMultiplayer/IMultiplayerServer.cs
+++ b/osu.Game/Online/RealtimeMultiplayer/IMultiplayerServer.cs
@@ -23,6 +23,7 @@ namespace osu.Game.Online.RealtimeMultiplayer
         /// Transfer the host of the currently joined room to another user in the room.
         /// </summary>
         /// <param name="userId">The new user which is to become host.</param>
+        /// <exception cref="NotHostException">A user other than the current host is attempting to transfer host.</exception>
         Task TransferHost(long userId);
 
         /// <summary>
@@ -41,6 +42,7 @@ namespace osu.Game.Online.RealtimeMultiplayer
         /// <summary>
         /// As the host of a room, start the match.
         /// </summary>
+        /// <exception cref="NotHostException">A user other than the current host is attempting to start the game.</exception>
         Task StartMatch();
     }
 }
diff --git a/osu.Game/Online/RealtimeMultiplayer/NotHostException.cs b/osu.Game/Online/RealtimeMultiplayer/NotHostException.cs
new file mode 100644
index 0000000000..e421c6ae28
--- /dev/null
+++ b/osu.Game/Online/RealtimeMultiplayer/NotHostException.cs
@@ -0,0 +1,15 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+
+namespace osu.Game.Online.RealtimeMultiplayer
+{
+    public class NotHostException : Exception
+    {
+        public NotHostException()
+            : base("User is attempting to perform a host level operation while not the host")
+        {
+        }
+    }
+}