From 6d15dcf1ca4a9f34d7d70dd6de08fde11b0a6cdd Mon Sep 17 00:00:00 2001
From: "Chris Ross (ASP.NET)" <chrross@microsoft.com>
Date: Fri, 26 Jan 2018 12:16:25 -0800
Subject: [PATCH] Use TryAdd for ISessionStore service #2755

---
 .../SessionServiceCollectionExtensions.cs                      | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.AspNetCore.Session/SessionServiceCollectionExtensions.cs b/src/Microsoft.AspNetCore.Session/SessionServiceCollectionExtensions.cs
index 48424e48cd..628390fbe3 100644
--- a/src/Microsoft.AspNetCore.Session/SessionServiceCollectionExtensions.cs
+++ b/src/Microsoft.AspNetCore.Session/SessionServiceCollectionExtensions.cs
@@ -4,6 +4,7 @@
 using System;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Session;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
@@ -24,7 +25,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 throw new ArgumentNullException(nameof(services));
             }
 
-            services.AddTransient<ISessionStore, DistributedSessionStore>();
+            services.TryAddTransient<ISessionStore, DistributedSessionStore>();
             services.AddDataProtection();
             return services;
         }