diff --git a/Facepunch.Steamworks/BaseSteamworks.cs b/Facepunch.Steamworks/BaseSteamworks.cs
index fbdf91f..8e95faf 100644
--- a/Facepunch.Steamworks/BaseSteamworks.cs
+++ b/Facepunch.Steamworks/BaseSteamworks.cs
@@ -81,13 +81,13 @@ namespace Facepunch.Steamworks
         /// <summary>
         /// Global callback type
         /// </summary>
-        internal void AddCallback<T, TSmall>( Action<T> Callback, int id )
+        internal void AddCallback<T, TSmall>( Action<T, bool> Callback, int id ) where T : new()
         {
             var callback = new Callback<T, TSmall>( native.api, IsGameServer, id, Callback );
             Disposables.Add( callback );
         }
 
-        internal void AddCallback<T>( Action<T> Callback, int id )
+        internal void AddCallback<T>( Action<T, bool> Callback, int id ) where T : new()
         {
             AddCallback<T, T>( Callback, id );
         }
diff --git a/Facepunch.Steamworks/Interfaces/Networking.cs b/Facepunch.Steamworks/Interfaces/Networking.cs
index 94d64d9..3a58293 100644
--- a/Facepunch.Steamworks/Interfaces/Networking.cs
+++ b/Facepunch.Steamworks/Interfaces/Networking.cs
@@ -47,7 +47,7 @@ namespace Facepunch.Steamworks
             }
         }
 
-        private void onP2PConnectionRequest( P2PSessionRequest o )
+        private void onP2PConnectionRequest( P2PSessionRequest o, bool b )
         {
             if ( OnIncomingConnection != null )
             {
@@ -83,7 +83,7 @@ namespace Facepunch.Steamworks
             Max = 5
         };
 
-        private void onP2PConnectionFailed( P2PSessionConnectFail o )
+        private void onP2PConnectionFailed( P2PSessionConnectFail o, bool b )
         {
             if ( OnConnectionFailed  != null )
             {
diff --git a/Facepunch.Steamworks/Interfaces/Workshop.cs b/Facepunch.Steamworks/Interfaces/Workshop.cs
index ba0ee58..520238e 100644
--- a/Facepunch.Steamworks/Interfaces/Workshop.cs
+++ b/Facepunch.Steamworks/Interfaces/Workshop.cs
@@ -37,13 +37,13 @@ namespace Facepunch.Steamworks
             OnItemInstalled = null;
         }
 
-        private void onItemInstalled( ItemInstalled obj )
+        private void onItemInstalled( ItemInstalled obj, bool failed )
         {
             if ( OnItemInstalled != null )
                 OnItemInstalled( obj.FileId );
         }
 
-        private void onDownloadResult( DownloadResult obj )
+        private void onDownloadResult( DownloadResult obj, bool failed )
         {
             if ( OnFileDownloaded != null )
                 OnFileDownloaded( obj.FileId, obj.Result );
diff --git a/Facepunch.Steamworks/Interop/Callback.This.cs b/Facepunch.Steamworks/Interop/Callback.This.cs
index 39b8464..88f6543 100644
--- a/Facepunch.Steamworks/Interop/Callback.This.cs
+++ b/Facepunch.Steamworks/Interop/Callback.This.cs
@@ -10,26 +10,29 @@ namespace Facepunch.Steamworks.Interop.VTable.This
     internal struct Callback
     {
         [UnmanagedFunctionPointer( CallingConvention.ThisCall )]    public delegate void Result( IntPtr thisptr, IntPtr pvParam );
+        [UnmanagedFunctionPointer( CallingConvention.ThisCall )]    public delegate void ResultBool( IntPtr thisptr, IntPtr pvParam, bool bIOFailure, SteamNative.SteamAPICall_t hSteamAPICall );
         [UnmanagedFunctionPointer( CallingConvention.ThisCall )]    public delegate int GetSize( IntPtr thisptr );
 
-        [MarshalAs(UnmanagedType.FunctionPtr)]  public Result RunCallResult;
+        [MarshalAs(UnmanagedType.FunctionPtr)]  public ResultBool RunCallResult;
         [MarshalAs(UnmanagedType.FunctionPtr)]  public Result RunCallback;
         [MarshalAs(UnmanagedType.FunctionPtr)]  public GetSize GetCallbackSizeBytes;
 
-        internal static IntPtr Get( Action<IntPtr, IntPtr> onRunCallback, int size, Interop.Callback cb )
+        internal static IntPtr Get( Action<IntPtr, IntPtr, bool> onRunCallback, int size, Interop.Callback cb )
         {
             var ptr = Marshal.AllocHGlobal( Marshal.SizeOf( typeof( Callback ) ) );
 
-            Callback.Result da = ( _, p ) => {  onRunCallback( _, p ); };
+            Callback.Result da = ( _, p ) => { onRunCallback( _, p, false ); };
+            Callback.ResultBool db = ( _, p, iofailure, call ) => { onRunCallback( _, p, iofailure ); };
             Callback.GetSize dc = ( _ ) => { return size; };
 
             cb.AddHandle( GCHandle.Alloc( da ) );
+            cb.AddHandle( GCHandle.Alloc( db ) );
             cb.AddHandle( GCHandle.Alloc( dc ) );
 
             var table = new Callback()
             {
                 RunCallback = da,
-                RunCallResult = da,
+                RunCallResult = db,
                 GetCallbackSizeBytes = dc
             };
 
diff --git a/Facepunch.Steamworks/Interop/Callback.cs b/Facepunch.Steamworks/Interop/Callback.cs
index 4f22b41..7896681 100644
--- a/Facepunch.Steamworks/Interop/Callback.cs
+++ b/Facepunch.Steamworks/Interop/Callback.cs
@@ -48,20 +48,20 @@ namespace Facepunch.Steamworks.Interop
         }
     }
 
-    internal partial class Callback<T, TSmall> : Callback
+    internal partial class Callback<T, TSmall> : Callback where T : new()
     {
         private SteamNative.SteamApi api;
 
         public int CallbackId = 0;
         public bool GameServer = false;
-        public Action<T> Function;
+        public Action<T, bool> Function;
 
         private IntPtr vTablePtr = IntPtr.Zero;
         private GCHandle callbackPin;
 
         private readonly int m_size = Marshal.SizeOf(typeof(T));
 
-        public Callback( SteamNative.SteamApi api, bool gameserver, int callbackid, Action<T> func )
+        public Callback( SteamNative.SteamApi api, bool gameserver, int callbackid, Action<T, bool> func )
         {
             this.api = api;
             GameServer = gameserver;
@@ -90,16 +90,22 @@ namespace Facepunch.Steamworks.Interop
             base.Dispose();
         }
 
-        private void OnRunCallback( IntPtr thisObject, IntPtr ptr )
+        private void OnRunCallback( IntPtr thisObject, IntPtr ptr, bool failure )
         {
             if ( callbackPin == null ) throw new System.Exception( "Callback wasn't pinned!" );
             if ( vTablePtr == IntPtr.Zero ) throw new System.Exception( "vTablePtr wasn't pinned!" );
-            if ( thisObject != IntPtr.Zero && thisObject != callbackPin.AddrOfPinnedObject() ) throw new System.Exception( "This wasn't valid!" );
+            if ( thisObject != IntPtr.Zero && thisObject != callbackPin.AddrOfPinnedObject() ) throw new System.Exception( "This wasn't valid! ("+ thisObject.ToInt64() + ") ( "+ callbackPin.AddrOfPinnedObject().ToInt64() + " )" );
 
             if ( SteamNative.Platform.PackSmall && typeof(T) != typeof( TSmall ) ) throw new System.Exception( "Callback should use PackSmall" );
 
+            if ( failure )
+            {
+                Function( new T(), failure );
+                return;
+            }
+
             T data = (T) Marshal.PtrToStructure( ptr, typeof(T) );
-            Function( data );
+            Function( data, failure );
         }
 
 
diff --git a/Facepunch.Steamworks/Server/Auth.cs b/Facepunch.Steamworks/Server/Auth.cs
index a5c8317..3448950 100644
--- a/Facepunch.Steamworks/Server/Auth.cs
+++ b/Facepunch.Steamworks/Server/Auth.cs
@@ -58,7 +58,7 @@ namespace Facepunch.Steamworks
             server.AddCallback<ValidateAuthTicketResponse>( OnAuthTicketValidate, ValidateAuthTicketResponse.CallbackId );
         }
 
-        void OnAuthTicketValidate( ValidateAuthTicketResponse data )
+        void OnAuthTicketValidate( ValidateAuthTicketResponse data, bool b )
         {
             if ( OnAuthChange != null )
                 OnAuthChange( data.SteamID, data.OwnerSteamID, (Status) data.AuthResponse );