diff --git a/src/SimpleInjector.Integration.AspNetCore.Mvc.Core/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs b/src/SimpleInjector.Integration.AspNetCore.Mvc.Core/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs
index 39dd934ed..574a97296 100644
--- a/src/SimpleInjector.Integration.AspNetCore.Mvc.Core/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs
+++ b/src/SimpleInjector.Integration.AspNetCore.Mvc.Core/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs
@@ -34,8 +34,8 @@ public static class SimpleInjectorAspNetCoreMvcIntegrationExtensions
             "—e.g. 'services.AddSimpleInjector(container, options => options.AddAspNetCore()." +
             nameof(SimpleInjectorAspNetCoreBuilderMvcCoreExtensions.AddControllerActivation) + "());'. " +
             "Please see https://simpleinjector.org/aspnetcore for more details. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
         public static void RegisterMvcControllers(
             this Container container, IApplicationBuilder applicationBuilder)
@@ -78,8 +78,8 @@ public static void RegisterMvcControllers(
             "—e.g. 'services.AddSimpleInjector(container, options => options.AddAspNetCore()." +
             nameof(SimpleInjectorAspNetCoreBuilderMvcCoreExtensions.AddViewComponentActivation) + "());'. " +
             "Please see https://simpleinjector.org/aspnetcore for more details. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
         public static void RegisterMvcViewComponents(
             this Container container, IApplicationBuilder applicationBuilder)
@@ -121,8 +121,8 @@ public static void RegisterMvcViewComponents(
             "—e.g. 'services.AddSimpleInjector(container, options => options.AddAspNetCore()." +
             nameof(SimpleInjectorAspNetCoreBuilderMvcCoreExtensions.AddViewComponentActivation) + "());'. " +
             "Please see https://simpleinjector.org/aspnetcore for more details. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
         public static void RegisterMvcViewComponents(
             this Container container, IViewComponentDescriptorProvider viewComponentDescriptorProvider)
diff --git a/src/SimpleInjector.Integration.AspNetCore.Mvc/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs b/src/SimpleInjector.Integration.AspNetCore.Mvc/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs
index dbed509cf..dce162776 100644
--- a/src/SimpleInjector.Integration.AspNetCore.Mvc/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs
+++ b/src/SimpleInjector.Integration.AspNetCore.Mvc/SimpleInjectorAspNetCoreMvcIntegrationExtensions.cs
@@ -41,8 +41,8 @@ public static class SimpleInjectorAspNetCoreMvcIntegrationExtensions
             "'services.AddSimpleInjector(container, options => options.AddAspNetCore()." +
             nameof(SimpleInjectorAspNetCoreBuilderMvcExtensions.AddTagHelperActivation) + "());'. " +
             "Please see https://simpleinjector.org/aspnetcore for more details. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
         public static void AddSimpleInjectorTagHelperActivation(
             this IServiceCollection services,
@@ -84,8 +84,8 @@ public static void AddSimpleInjectorTagHelperActivation(
             "'services.AddSimpleInjector(container, options => options.AddAspNetCore()." +
             nameof(SimpleInjectorAspNetCoreBuilderMvcExtensions.AddPageModelActivation) + "());'. " +
             "Please see https://simpleinjector.org/aspnetcore for more details. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
         public static void RegisterPageModels(
             this Container container, IApplicationBuilder applicationBuilder)
diff --git a/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorAspNetIntegrationExtensions.cs b/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorAspNetIntegrationExtensions.cs
index 7c920a976..45a0a7009 100644
--- a/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorAspNetIntegrationExtensions.cs
+++ b/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorAspNetIntegrationExtensions.cs
@@ -106,8 +106,8 @@ public static T GetRequiredRequestService<T>(this IApplicationBuilder builder)
         [Obsolete("Please call services.AddSimpleInjector() instead. AddSimpleInjector can be called from " +
             "within the ConfigureServices method of the Startup class. " +
             "See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void EnableSimpleInjectorCrossWiring(
             this IServiceCollection services, Container container)
         {
@@ -130,8 +130,8 @@ public static void EnableSimpleInjectorCrossWiring(
         [Obsolete("Please call services.AddSimpleInjector(options => { options.CrossWire<TService>(); }) " +
             "instead. AddSimpleInjector can be called from within the ConfigureServices method of the " +
             "Startup class. See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void CrossWire<TService>(this Container container, IApplicationBuilder builder)
             where TService : class
         {
@@ -148,8 +148,8 @@ public static void CrossWire<TService>(this Container container, IApplicationBui
         [Obsolete("Please call services.AddSimpleInjector(options => { options.CrossWire(typeof(YourType));" +
             " }) instead. AddSimpleInjector can be called from within the ConfigureServices method of the " +
             "Startup class. See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void CrossWire(this Container container, Type serviceType, IApplicationBuilder builder)
         {
             Requires.IsNotNull(container, nameof(container));
@@ -258,8 +258,8 @@ public static IApplicationBuilder UseMiddleware(
         [Obsolete("Please call services.AddSimpleInjector() instead. AddSimpleInjector can be called from " +
             "within the ConfigureServices method of the Startup class. It ensures auto cross wiring is " +
             "enabled. See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void AutoCrossWireAspNetComponents(this Container container, IApplicationBuilder app)
         {
             Requires.IsNotNull(app, nameof(app));
@@ -278,8 +278,8 @@ public static void AutoCrossWireAspNetComponents(this Container container, IAppl
         [Obsolete("Please call services.AddSimpleInjector() instead. AddSimpleInjector can be called from " +
             "within the ConfigureServices method of the Startup class. It ensures auto cross wiring is " +
             "enabled. See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void AutoCrossWireAspNetComponents(
             this Container container, IServiceProvider appServices)
         {
diff --git a/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorUseOptionsAspNetCoreExtensions.cs b/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorUseOptionsAspNetCoreExtensions.cs
index 3757cee37..affd2cb96 100644
--- a/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorUseOptionsAspNetCoreExtensions.cs
+++ b/src/SimpleInjector.Integration.AspNetCore/SimpleInjectorUseOptionsAspNetCoreExtensions.cs
@@ -85,8 +85,8 @@ public static IApplicationBuilder UseSimpleInjector(
             "call). Instead, take care that you call .UseMiddleware<TMiddleware>(Container) at the right " +
             "stage. This typically means after .UseStaticFiles() and .UseAuthorization(), but before " +
             ".UseEndpoints(...). See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void UseMiddleware<TMiddleware>(
             this SimpleInjectorUseOptions options, IApplicationBuilder app)
             where TMiddleware : class, IMiddleware
@@ -111,8 +111,8 @@ public static void UseMiddleware<TMiddleware>(
             "call). Instead, take care that you call .UseMiddleware<TMiddleware>(Container) at the right " +
             "stage. This typically means after .UseStaticFiles() and .UseAuthorization(), but before " +
             ".UseEndpoints(...). See https://simpleinjector.org/aspnetcore for more information. " +
-            "Will be treated as an error from version 4.9. Will be removed in version 5.0.",
-            error: false)]
+            "Will be removed in version 5.0.",
+            error: true)]
         public static void UseMiddleware(
             this SimpleInjectorUseOptions options, Type middlewareType, IApplicationBuilder app)
         {