Use codebehind class for the the user management component.

templates/app/aspnet-core/src/MyCompanyName.MyProjectName.Blazor/Pages/UserManagement.razor

@@ -17,16 +17,4 @@
         }
     </ul>
     <p>Total user count: @_totalUserCount</p>
-}
-
-@code {
-    private long _totalUserCount = 0;
-    private IReadOnlyList<IdentityUserDto> _users;
-
-    private async Task GetUsersAsync()
-    {
-        var result = await UserAppService.GetListAsync(new GetIdentityUsersInput());
-        _totalUserCount = result.TotalCount;
-        _users = result.Items;
-    }
 }

templates/app/aspnet-core/src/MyCompanyName.MyProjectName.Blazor/Pages/UserManagement.razor.cs

@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components;
+using Volo.Abp.Identity;
+
+namespace MyCompanyName.MyProjectName.Blazor.Pages
+{
+    public partial class UserManagement : ComponentBase
+    {
+        private long _totalUserCount;
+        private IReadOnlyList<IdentityUserDto> _users;
+        
+        private async Task GetUsersAsync()
+        {
+            var result = await UserAppService.GetListAsync(new GetIdentityUsersInput());
+            _totalUserCount = result.TotalCount;
+            _users = result.Items;
+        }
+    }
+}