From bb62621f3738dff68eee643d7a5069913bae6a09 Mon Sep 17 00:00:00 2001
From: Safia Abdalla <safia@microsoft.com>
Date: Mon, 31 Aug 2020 17:16:36 +0000
Subject: [PATCH] Add guard checks to PageLoaderMatcherPolicy when loader
 returns asynchronously (#25370)

---
 .../src/Infrastructure/PageLoaderMatcherPolicy.cs            | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Mvc/Mvc.RazorPages/src/Infrastructure/PageLoaderMatcherPolicy.cs b/src/Mvc/Mvc.RazorPages/src/Infrastructure/PageLoaderMatcherPolicy.cs
index 18c14db7c6..0744a11755 100644
--- a/src/Mvc/Mvc.RazorPages/src/Infrastructure/PageLoaderMatcherPolicy.cs
+++ b/src/Mvc/Mvc.RazorPages/src/Infrastructure/PageLoaderMatcherPolicy.cs
@@ -111,6 +111,11 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             for (var i = index + 1; i < candidates.Count; i++)
             {
+                if (!candidates.IsValidCandidate(i))
+                {
+                    continue;
+                }
+
                 var candidate = candidates[i];
                 var endpoint = candidate.Endpoint;