diff --git a/src/Umbraco.Core/Persistence/EntityNotFoundException.cs b/src/Umbraco.Core/Persistence/EntityNotFoundException.cs
new file mode 100644
index 0000000000..1cc66a2ba2
--- /dev/null
+++ b/src/Umbraco.Core/Persistence/EntityNotFoundException.cs
@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Umbraco.Core.Persistence
+{
+
+    //TODO: Would be good to use this exception type anytime we cannot find an entity
+
+    /// <summary>
+    /// An exception used to indicate that an umbraco entity could not be found
+    /// </summary>
+    public class EntityNotFoundException : Exception
+    {
+        public object Id { get; private set; }
+        private readonly string _msg;
+
+        public EntityNotFoundException(object id, string msg)
+        {
+            Id = id;
+            _msg = msg;
+        }
+
+        public EntityNotFoundException(string msg)
+        {
+            _msg = msg;
+        }
+
+        public override string Message
+        {
+            get { return _msg; }
+        }
+
+        public override string ToString()
+        {
+            var result = base.ToString();
+
+            if (Id != null)
+            {
+                return "Umbraco entity (id: " + Id + ") not found. " + result;    
+            }
+
+            return result;
+        }
+    }
+}
diff --git a/src/Umbraco.Core/Services/UserService.cs b/src/Umbraco.Core/Services/UserService.cs
index 1c59e33d6a..21421a1936 100644
--- a/src/Umbraco.Core/Services/UserService.cs
+++ b/src/Umbraco.Core/Services/UserService.cs
@@ -51,7 +51,7 @@ namespace Umbraco.Core.Services
 
                 if (types.Any() == false)
                 {
-                    throw new InvalidOperationException("No member types could be resolved");
+                    throw new EntityNotFoundException("No member types could be resolved");
                 }
 
                 if (types.InvariantContains("writer"))
@@ -126,7 +126,7 @@ namespace Umbraco.Core.Services
             var userType = GetUserTypeByAlias(memberTypeAlias);
             if (userType == null)
             {
-                throw new ArgumentException("The user type " + memberTypeAlias + " could not be resolved");
+                throw new EntityNotFoundException("The user type " + memberTypeAlias + " could not be resolved");
             }
 
             return CreateMemberWithIdentity(username, email, password, userType);
diff --git a/src/Umbraco.Core/Umbraco.Core.csproj b/src/Umbraco.Core/Umbraco.Core.csproj
index 21385ac39c..0cb85f416d 100644
--- a/src/Umbraco.Core/Umbraco.Core.csproj
+++ b/src/Umbraco.Core/Umbraco.Core.csproj
@@ -354,6 +354,7 @@
     <Compile Include="Models\TemplateNode.cs" />
     <Compile Include="Models\UmbracoEntityExtensions.cs" />
     <Compile Include="Packaging\PackageBinaryInspector.cs" />
+    <Compile Include="Persistence\EntityNotFoundException.cs" />
     <Compile Include="Persistence\Factories\MemberGroupFactory.cs" />
     <Compile Include="Persistence\Mappers\MemberGroupMapper.cs" />
     <Compile Include="PropertyEditors\DefaultPropertyValueConverterAttribute.cs" />
diff --git a/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs b/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs
index 04c7b39829..69cef03ab4 100644
--- a/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs
+++ b/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs
@@ -8,6 +8,7 @@ using System.Web.Http;
 using Umbraco.Core;
 using Umbraco.Core.Models;
 using Umbraco.Core.Models.EntityBase;
+using Umbraco.Core.Persistence;
 using Umbraco.Web.Models.Trees;
 using Umbraco.Web.WebApi.Filters;
 using umbraco;
@@ -88,6 +89,10 @@ namespace Umbraco.Web.Trees
             {
                 //just return their single start node, it will show up under the 'Content' label
                 var startNode = Services.EntityService.Get(UserStartNode, UmbracoObjectType);
+                if (startNode == null)
+                {
+                    throw new EntityNotFoundException(UserStartNode, "User's start content node could not be found");
+                }
                 return new[] { startNode };
             }