From @Thezork #1015

Author: nulltoken

LibGit2Sharp/Core/GitSmartSubtransportRegistration.cs

@@ -8,9 +8,11 @@ internal class GitSmartSubtransportRegistration
     {
         public IntPtr SubtransportCallback;
         public uint Rpc;
+        public uint Param;
 
         public delegate int create_callback(
             out IntPtr subtransport,
-            IntPtr transport);
+            IntPtr transport,
+            IntPtr param);
     }
 }

LibGit2Sharp/SmartSubtransportRegistration.cs

@@ -80,7 +80,8 @@ private static class EntryPoints
 
             private static int Subtransport(
                 out IntPtr subtransport,
-                IntPtr transport)
+                IntPtr transport,
+                IntPtr payload)
             {
                 subtransport = IntPtr.Zero;