From ea607994b85612bc09bc6551ba2988bf0c8c264b Mon Sep 17 00:00:00 2001
From: Ivan Wennberg <ivan.wennberg@nhn.no>
Date: Thu, 23 Apr 2026 12:13:38 +0200
Subject: [PATCH 1/2] Fix #2173: Honor AbortOnConnectFail on sentinel path

---
 .../ConnectionMultiplexer.Sentinel.cs         | 15 ++++++-
 .../SentinelAbortOnConnectTests.cs            | 41 +++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 tests/StackExchange.Redis.Tests/SentinelAbortOnConnectTests.cs

diff --git a/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs b/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs
index 61b36b014..8a30ae8c4 100644
--- a/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs
+++ b/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs
@@ -166,7 +166,8 @@ private static async Task<ConnectionMultiplexer> SentinelPrimaryConnectAsync(Con
     /// <param name="log">The writer to log to, if any.</param>
     public ConnectionMultiplexer GetSentinelMasterConnection(ConfigurationOptions config, TextWriter? log = null)
     {
-        if (ServerSelectionStrategy.ServerType != ServerType.Sentinel)
+        if (ServerSelectionStrategy.ServerType != ServerType.Sentinel
+            && (RawConfig.AbortOnConnectFail || IsConnected))
         {
             throw new RedisConnectionException(
                 ConnectionFailureType.UnableToConnect,
@@ -203,6 +204,18 @@ public ConnectionMultiplexer GetSentinelMasterConnection(ConfigurationOptions co
 
             if (newPrimaryEndPoint is null)
             {
+                if (!config.AbortOnConnectFail)
+                {
+                    connection = ConnectImpl(config, log, endpoints: config.EndPoints);
+                    connection.ConnectionRestored += OnManagedConnectionRestored;
+                    connection.ConnectionFailed += OnManagedConnectionFailed;
+                    lock (sentinelConnectionChildren)
+                    {
+                        sentinelConnectionChildren[serviceName] = connection;
+                    }
+                    return connection;
+                }
+
                 throw new RedisConnectionException(
                     ConnectionFailureType.UnableToConnect,
                     $"Sentinel: Failed connecting to configured primary for service: {config.ServiceName}");
diff --git a/tests/StackExchange.Redis.Tests/SentinelAbortOnConnectTests.cs b/tests/StackExchange.Redis.Tests/SentinelAbortOnConnectTests.cs
new file mode 100644
index 000000000..e6ff1b7e1
--- /dev/null
+++ b/tests/StackExchange.Redis.Tests/SentinelAbortOnConnectTests.cs
@@ -0,0 +1,41 @@
+using System.Threading.Tasks;
+using Xunit;
+
+namespace StackExchange.Redis.Tests;
+
+public class SentinelAbortOnConnectTests(ITestOutputHelper output) : TestBase(output)
+{
+    [Fact]
+    public void ConnectToUnreachableSentinelReturnsDisconnectedMultiplexer()
+    {
+        var config = ConfigurationOptions.Parse("nonexistent:26379,serviceName=mymaster");
+        config.AbortOnConnectFail = false;
+        config.ConnectTimeout = 1000;
+
+        using var mux = ConnectionMultiplexer.Connect(config);
+        Assert.NotNull(mux);
+        Assert.False(mux.IsConnected);
+    }
+
+    [Fact]
+    public async Task ConnectAsyncToUnreachableSentinelReturnsDisconnectedMultiplexer()
+    {
+        var config = ConfigurationOptions.Parse("nonexistent:26379,serviceName=mymaster");
+        config.AbortOnConnectFail = false;
+        config.ConnectTimeout = 1000;
+
+        await using var mux = await ConnectionMultiplexer.ConnectAsync(config);
+        Assert.NotNull(mux);
+        Assert.False(mux.IsConnected);
+    }
+
+    [Fact]
+    public void ConnectToUnreachableSentinelThrowsWhenAbortOnConnectFailIsTrue()
+    {
+        var config = ConfigurationOptions.Parse("nonexistent:26379,serviceName=mymaster");
+        config.AbortOnConnectFail = true;
+        config.ConnectTimeout = 1000;
+
+        Assert.Throws<RedisConnectionException>(() => ConnectionMultiplexer.Connect(config));
+    }
+}

From 7ac12a8ebd693baed3fd5a207ac6e347890938b3 Mon Sep 17 00:00:00 2001
From: Ivan Wennberg <ivan.wennberg@nhn.no>
Date: Thu, 23 Apr 2026 13:15:18 +0200
Subject: [PATCH 2/2] Clone endpoints to avoid mutating caller's
 ConfigurationOptions

---
 src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs b/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs
index 8a30ae8c4..593adc2ff 100644
--- a/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs
+++ b/src/StackExchange.Redis/ConnectionMultiplexer.Sentinel.cs
@@ -206,7 +206,7 @@ public ConnectionMultiplexer GetSentinelMasterConnection(ConfigurationOptions co
             {
                 if (!config.AbortOnConnectFail)
                 {
-                    connection = ConnectImpl(config, log, endpoints: config.EndPoints);
+                    connection = ConnectImpl(config, log, endpoints: config.EndPoints.Clone());
                     connection.ConnectionRestored += OnManagedConnectionRestored;
                     connection.ConnectionFailed += OnManagedConnectionFailed;
                     lock (sentinelConnectionChildren)