diff --git a/source/Halibut.Tests.DotMemory/Halibut.Tests.DotMemory.csproj b/source/Halibut.Tests.DotMemory/Halibut.Tests.DotMemory.csproj
index cbd3546a..84fb9e31 100644
--- a/source/Halibut.Tests.DotMemory/Halibut.Tests.DotMemory.csproj
+++ b/source/Halibut.Tests.DotMemory/Halibut.Tests.DotMemory.csproj
@@ -39,7 +39,7 @@
         <PackageReference Include="Serilog.Sinks.NUnit" Version="1.0.3" />
         <PackageReference Include="System.Diagnostics.PerformanceCounter" Version="6.0.1" />
         <PackageReference Include="TeamCity.VSTest.TestAdapter" Version="1.0.36" />
-        <PackageReference Include="Serilog" Version="2.12.0" />
+        <PackageReference Include="Serilog" Version="4.1.0" />
         <PackageReference Include="Serilog.Sinks.ColoredConsole" Version="3.0.1" />
         <PackageReference Include="Octopus.Shellfish" Version="0.2.1180" />
     </ItemGroup>
diff --git a/source/Halibut.Tests/Halibut.Tests.csproj b/source/Halibut.Tests/Halibut.Tests.csproj
index a89c6a6e..4862ad72 100644
--- a/source/Halibut.Tests/Halibut.Tests.csproj
+++ b/source/Halibut.Tests/Halibut.Tests.csproj
@@ -44,10 +44,11 @@
     <PackageReference Include="NUnit3TestAdapter" Version="4.4.2" />
     <PackageReference Include="Serilog.Extensions.Logging" Version="7.0.0" />
     <PackageReference Include="Serilog.Sinks.NUnit" Version="1.0.3" />
+    <PackageReference Include="Serilog.Sinks.TextWriter" Version="3.0.0" />
     <PackageReference Include="System.Diagnostics.PerformanceCounter" Version="6.0.1" />
     <PackageReference Include="System.Interactive.Async" Version="6.0.1" />
     <PackageReference Include="TeamCity.VSTest.TestAdapter" Version="1.0.36" />
-    <PackageReference Include="Serilog" Version="2.12.0" />
+    <PackageReference Include="Serilog" Version="4.1.0" />
     <PackageReference Include="Serilog.Sinks.ColoredConsole" Version="3.0.1" />
   </ItemGroup>
 
diff --git a/source/Halibut.Tests/Support/BackwardsCompatibility/LatestClientAndPreviousServiceVersionBuilder.cs b/source/Halibut.Tests/Support/BackwardsCompatibility/LatestClientAndPreviousServiceVersionBuilder.cs
index 4d0d041d..e2a3c904 100644
--- a/source/Halibut.Tests/Support/BackwardsCompatibility/LatestClientAndPreviousServiceVersionBuilder.cs
+++ b/source/Halibut.Tests/Support/BackwardsCompatibility/LatestClientAndPreviousServiceVersionBuilder.cs
@@ -1,12 +1,17 @@
 using System;
+using System.Collections.Concurrent;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
+using Halibut.Diagnostics;
 using Halibut.Diagnostics.LogCreators;
 using Halibut.Logging;
 using Halibut.TestProxy;
 using Halibut.Tests.Support.Logging;
 using Halibut.Transport.Proxy;
 using Octopus.TestPortForwarder;
+using Serilog;
+using ILog = Halibut.Diagnostics.ILog;
 
 namespace Halibut.Tests.Support.BackwardsCompatibility
 {
@@ -21,6 +26,7 @@ public class LatestClientAndPreviousServiceVersionBuilder : IClientAndServiceBui
         ProxyFactory? proxyFactory;
         Reference<HttpProxyService>? proxyServiceReference;
         LogLevel halibutLogLevel = LogLevel.Trace;
+        StringWriter? loggerStringWriter;
         readonly OldServiceAvailableServices availableServices = new(false, false);
         
         LatestClientAndPreviousServiceVersionBuilder(ServiceConnectionType serviceConnectionType, CertAndThumbprint serviceCertAndThumbprint)
@@ -59,6 +65,12 @@ public static LatestClientAndPreviousServiceVersionBuilder ForServiceConnectionT
             }
         }
 
+        public LatestClientAndPreviousServiceVersionBuilder RecordingLogs(out StringWriter stringWriter)
+        {
+            loggerStringWriter = stringWriter = new();
+            return this;
+        }
+        
         public LatestClientAndPreviousServiceVersionBuilder WithServiceVersion(Version? version)
         {
             this.version = version;
@@ -149,7 +161,11 @@ async Task<IClientAndService> IClientAndServiceBuilder.Build(CancellationToken c
         
         public async Task<ClientAndService> Build(CancellationToken cancellationToken)
         {
-            var logger = new SerilogLoggerBuilder().Build().ForContext<LatestClientAndPreviousServiceVersionBuilder>();
+            var logger = loggerStringWriter == null
+                ? new SerilogLoggerBuilder()
+                    .Build().ForContext<LatestClientAndPreviousServiceVersionBuilder>()
+                : new LoggerConfiguration().WriteTo.TextWriter(loggerStringWriter).CreateLogger();
+            
             CancellationTokenSource cancellationTokenSource = new();
             if (version == null)
             {
diff --git a/source/Halibut.Tests/TlsFixture.cs b/source/Halibut.Tests/TlsFixture.cs
index ffc332f0..f6d9f057 100644
--- a/source/Halibut.Tests/TlsFixture.cs
+++ b/source/Halibut.Tests/TlsFixture.cs
@@ -22,6 +22,7 @@
 using FluentAssertions;
 using Halibut.Exceptions;
 using Halibut.Tests.Support;
+using Halibut.Tests.Support.BackwardsCompatibility;
 using Halibut.Tests.Support.TestAttributes;
 using Halibut.Tests.Support.TestCases;
 using Halibut.Tests.TestServices.Async;
@@ -62,5 +63,26 @@ public async Task LatestClientAndServiceUseBestAvailableSslProtocol(ClientAndSer
                     .Should().Contain(logEvent => logEvent.FormattedMessage.Contains($"using protocol {expectedSslProtocol}"));
             }
         }
+        
+        [Test]
+        // [PreviousClientAndLatestServiceVersionsTestCases(testNetworkConditions: false)]
+        [LatestClientAndPreviousServiceVersionsTestCases(testNetworkConditions: false)]
+        public async Task PreviousClientXorServiceUsageMakeSslProtocolFallBackOnTls12(ClientAndServiceTestCase clientAndServiceTestCase)
+        {
+            await using (var clientAndService = await ((LatestClientAndPreviousServiceVersionBuilder)(clientAndServiceTestCase.CreateTestCaseBuilder()
+                             .WithStandardServices()))
+                             .RecordingLogs(out var stringWriter)
+                             .Build(CancellationToken))
+            {
+                var echo = clientAndService.CreateAsyncClient<IEchoService, IAsyncClientEchoService>();
+                await echo.SayHelloAsync("World");
+                const SslProtocols expectedProtocol = SslProtocols.Tls12;
+                var expectedLogFragment = clientAndServiceTestCase.ServiceConnectionType == ServiceConnectionType.Listening
+                    ? $"client connected with {expectedProtocol}"
+                    : $"using protocol {expectedProtocol}";
+                var logs = stringWriter.ToString();
+                logs.Should().Contain(expectedLogFragment);
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/source/Octopus.TestPortForwarder/Octopus.TestPortForwarder.csproj b/source/Octopus.TestPortForwarder/Octopus.TestPortForwarder.csproj
index b9a5fa5f..405b6263 100644
--- a/source/Octopus.TestPortForwarder/Octopus.TestPortForwarder.csproj
+++ b/source/Octopus.TestPortForwarder/Octopus.TestPortForwarder.csproj
@@ -14,7 +14,7 @@
         <TargetFramework>net8.0</TargetFramework>
     </PropertyGroup>
     <ItemGroup>
-        <PackageReference Include="Serilog" Version="2.12.0" />
+        <PackageReference Include="Serilog" Version="4.1.0" />
     </ItemGroup>
 
     <PropertyGroup Condition=" '$(TargetFramework)' == 'net48' ">