diff --git a/src/libraries/Microsoft.Extensions.Hosting.Abstractions/src/IHostBuilder.cs b/src/libraries/Microsoft.Extensions.Hosting.Abstractions/src/IHostBuilder.cs
index 4d3cd6016bcd84..dedaf5d3be0874 100644
--- a/src/libraries/Microsoft.Extensions.Hosting.Abstractions/src/IHostBuilder.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting.Abstractions/src/IHostBuilder.cs
@@ -59,7 +59,15 @@ public interface IHostBuilder
         /// <typeparam name="TContainerBuilder">The type of builder.</typeparam>
         /// <param name="factory">The factory to register.</param>
         /// <returns>The same instance of the <see cref="IHostBuilder"/> for chaining.</returns>
+#if NET
+        IHostBuilder UseServiceProviderFactory<TContainerBuilder>(Func<HostBuilderContext, IServiceProviderFactory<TContainerBuilder>> factory) where TContainerBuilder : notnull
+        {
+            ArgumentNullException.ThrowIfNull(factory);
+            throw new NotSupportedException($"The type '{GetType()}' does not support '{nameof(UseServiceProviderFactory)}' with a context-based factory. Override this method to provide an implementation.");
+        }
+#else
         IHostBuilder UseServiceProviderFactory<TContainerBuilder>(Func<HostBuilderContext, IServiceProviderFactory<TContainerBuilder>> factory) where TContainerBuilder : notnull;
+#endif
 
         /// <summary>
         /// Enables configuring the instantiated dependency container. This can be called multiple times and
diff --git a/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/HostBuilderContextTests.cs b/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/HostBuilderContextTests.cs
index 44903b3aca6760..677bf5a0561e2a 100644
--- a/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/HostBuilderContextTests.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/HostBuilderContextTests.cs
@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.FileProviders;
 using Xunit;
 
@@ -102,4 +103,62 @@ private class TestHostEnvironment : IHostEnvironment
             public IFileProvider ContentRootFileProvider { get; set; } = null!;
         }
     }
+
+#if NET
+    /// <summary>
+    /// Tests the default interface method (DIM) for <see cref="IHostBuilder.UseServiceProviderFactory{TContainerBuilder}(Func{HostBuilderContext, IServiceProviderFactory{TContainerBuilder}})"/>.
+    /// This DIM ensures old IHostBuilder implementations (e.g., from Microsoft.Extensions.Hosting 2.2.0.0) can be
+    /// loaded without TypeLoadException on .NET even though they only implement the non-Func overload.
+    /// </summary>
+    public class IHostBuilderDefaultInterfaceMethodTests
+    {
+        [Fact]
+        public void UseServiceProviderFactory_FuncOverload_WithoutOverride_ThrowsNotSupportedException()
+        {
+            IHostBuilder builder = new MinimalHostBuilder();
+            Assert.Throws<NotSupportedException>(() => builder.UseServiceProviderFactory<IServiceCollection>(
+                _ => new MinimalServiceProviderFactory()));
+        }
+
+        [Fact]
+        public void UseServiceProviderFactory_FuncOverload_WithNullFactory_ThrowsArgumentNullException()
+        {
+            IHostBuilder builder = new MinimalHostBuilder();
+            Func<HostBuilderContext, IServiceProviderFactory<IServiceCollection>>? factory = null;
+            AssertExtensions.Throws<ArgumentNullException>("factory", () => builder.UseServiceProviderFactory<IServiceCollection>(factory));
+        }
+
+        [Fact]
+        public void UseServiceProviderFactory_NonFuncOverload_WithoutDIM_CanBeImplementedAndCalled()
+        {
+            IHostBuilder builder = new MinimalHostBuilder();
+            // This overload does not have a DIM and the MinimalHostBuilder provides its own implementation.
+            Assert.Same(builder, builder.UseServiceProviderFactory(new MinimalServiceProviderFactory()));
+        }
+
+        /// <summary>
+        /// Simulates an old IHostBuilder implementation (e.g., from v2.2) that only implements the
+        /// non-Func overload of UseServiceProviderFactory. The Func overload falls back to the DIM.
+        /// </summary>
+        private class MinimalHostBuilder : IHostBuilder
+        {
+            public IDictionary<object, object> Properties { get; } = new Dictionary<object, object>();
+
+            public IHostBuilder ConfigureAppConfiguration(Action<HostBuilderContext, IConfigurationBuilder> configureDelegate) => this;
+            public IHostBuilder ConfigureContainer<TContainerBuilder>(Action<HostBuilderContext, TContainerBuilder> configureDelegate) => this;
+            public IHostBuilder ConfigureHostConfiguration(Action<IConfigurationBuilder> configureDelegate) => this;
+            public IHostBuilder ConfigureServices(Action<HostBuilderContext, IServiceCollection> configureDelegate) => this;
+            public IHostBuilder UseServiceProviderFactory<TContainerBuilder>(IServiceProviderFactory<TContainerBuilder> factory) where TContainerBuilder : notnull => this;
+            // Note: UseServiceProviderFactory(Func<...>) is intentionally not overridden here;
+            // the DIM on IHostBuilder provides the fallback implementation.
+            public IHost Build() => null!;
+        }
+
+        private class MinimalServiceProviderFactory : IServiceProviderFactory<IServiceCollection>
+        {
+            public IServiceCollection CreateBuilder(IServiceCollection services) => services;
+            public IServiceProvider CreateServiceProvider(IServiceCollection containerBuilder) => null!;
+        }
+    }
+#endif
 }
diff --git a/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/Microsoft.Extensions.Hosting.Abstractions.Tests.csproj b/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/Microsoft.Extensions.Hosting.Abstractions.Tests.csproj
index ca92d0164b5fbd..6e3037bad5e40a 100644
--- a/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/Microsoft.Extensions.Hosting.Abstractions.Tests.csproj
+++ b/src/libraries/Microsoft.Extensions.Hosting.Abstractions/tests/Microsoft.Extensions.Hosting.Abstractions.Tests.csproj
@@ -7,10 +7,7 @@
 
   <ItemGroup>
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Configuration\src\Microsoft.Extensions.Configuration.csproj" />
-  </ItemGroup>
-
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
-    <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Hosting.Abstractions\src\Microsoft.Extensions.Hosting.Abstractions.csproj" />
+    <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Hosting.Abstractions\src\Microsoft.Extensions.Hosting.Abstractions.csproj" SkipUseReferenceAssembly="true" />
   </ItemGroup>
 
 </Project>