Updated following PR review.

src/Umbraco.Tests.UnitTests/Umbraco.Web.BackOffice/Filters/AppendUserModifiedHeaderAttributeTests.cs

@@ -8,6 +8,7 @@ using Microsoft.AspNetCore.Routing;
 using Moq;
 using NUnit.Framework;
 using Umbraco.Core.Models.Membership;
+using Umbraco.Web;
 using Umbraco.Web.BackOffice.Filters;
 using Umbraco.Web.Security;
 
@@ -95,10 +96,20 @@ namespace Umbraco.Tests.UnitTests.Umbraco.Web.BackOffice.Filters
                 .SetupGet(x => x.CurrentUser)
                 .Returns(currentUserMock.Object);
 
+            var umbracoContextMock = new Mock<IUmbracoContext>();
+            umbracoContextMock
+                .SetupGet(x => x.Security)
+                .Returns(webSecurityMock.Object);
+
+            var umbracoContextAccessorMock = new Mock<IUmbracoContextAccessor>();
+            umbracoContextAccessorMock
+                .SetupGet(x => x.UmbracoContext)
+                .Returns(umbracoContextMock.Object);
+
             var serviceProviderMock = new Mock<IServiceProvider>();
             serviceProviderMock
-                .Setup(x => x.GetService(typeof(IWebSecurity)))
-                .Returns(webSecurityMock.Object);
+                .Setup(x => x.GetService(typeof(IUmbracoContextAccessor)))
+                .Returns(umbracoContextAccessorMock.Object);
 
             httpContext.RequestServices = serviceProviderMock.Object;
 

src/Umbraco.Web.BackOffice/Filters/AppendUserModifiedHeaderAttribute.cs

@@ -2,7 +2,6 @@
 using Microsoft.AspNetCore.Mvc.Filters;
 using Microsoft.Extensions.DependencyInjection;
 using Umbraco.Core;
-using Umbraco.Web.Security;
 
 namespace Umbraco.Web.BackOffice.Filters
 {
@@ -43,8 +42,8 @@ namespace Umbraco.Web.BackOffice.Filters
                     throw new InvalidOperationException($"No argument found for the current action with the name: {_userIdParameter}");
                 }
 
-                var webSecurityService = context.HttpContext.RequestServices.GetService<IWebSecurity>();
-                var user = webSecurityService.CurrentUser;
+                var umbracoContextAccessor = context.HttpContext.RequestServices.GetService<IUmbracoContextAccessor>();
+                var user = umbracoContextAccessor.UmbracoContext.Security.CurrentUser;
                 if (user == null)
                 {
                     return;

src/Umbraco.Web.BackOffice/Filters/ValidationFilterAttribute.cs

@@ -12,7 +12,7 @@ namespace Umbraco.Web.BackOffice.Filters
         public override void OnActionExecuting(ActionExecutingContext context)
         {
             var modelState = context.ModelState;
-            if (!context.ModelState.IsValid)
+            if (!modelState.IsValid)
             {
                 context.Result = new BadRequestObjectResult(modelState);
             }