diff --git a/src/Umbraco.Web/Editors/MediaController.cs b/src/Umbraco.Web/Editors/MediaController.cs
index 1f95034c34..5dd0c3073f 100644
--- a/src/Umbraco.Web/Editors/MediaController.cs
+++ b/src/Umbraco.Web/Editors/MediaController.cs
@@ -195,7 +195,7 @@ namespace Umbraco.Web.Editors
                 }
                 else
                 {
-                    throw new EntityNotFoundException(id, "The passed id doesn't exist");
+                    throw new HttpResponseException(HttpStatusCode.NotFound);
                 }
             }
             else if (int.TryParse(id, out idInt))
@@ -203,7 +203,7 @@ namespace Umbraco.Web.Editors
                 return getChildren(idInt, pageNumber, pageSize, orderBy, orderDirection, orderBySystemField, filter);
             }
 
-            throw new InvalidCastException("Id must be either an integer or a Guid");
+            throw new HttpResponseException(HttpStatusCode.NotFound);
         }
 
         private PagedResult<ContentItemBasic<ContentPropertyBasic, IMedia>> getChildren(int id,
diff --git a/src/Umbraco.Web/Editors/MediaTypeController.cs b/src/Umbraco.Web/Editors/MediaTypeController.cs
index a40b83c9ea..67b8ae6d1f 100644
--- a/src/Umbraco.Web/Editors/MediaTypeController.cs
+++ b/src/Umbraco.Web/Editors/MediaTypeController.cs
@@ -182,16 +182,16 @@ namespace Umbraco.Web.Editors
             int idInt;
             if (Guid.TryParse(contentId, out idGuid)) { 
                 var entity = ApplicationContext.Services.EntityService.GetByKey(idGuid);
-                return getAllowedChildren(entity.Id);
+                return GetAllowedChildrenInternal(entity.Id);
             } else if (int.TryParse(contentId, out idInt))
             {
-                return getAllowedChildren(idInt);
+                return GetAllowedChildrenInternal(idInt);
             }
 
-            throw new InvalidCastException("Id must be either an integer or a Guid");
+            throw new HttpResponseException(HttpStatusCode.NotFound);
         }
 
-        private IEnumerable<ContentTypeBasic> getAllowedChildren(int contentId)
+        private IEnumerable<ContentTypeBasic> GetAllowedChildrenInternal(int contentId)
         {
             if (contentId == Constants.System.RecycleBinContent)
                 return Enumerable.Empty<ContentTypeBasic>();
diff --git a/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs b/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs
index 99ec60be75..027e4e488c 100644
--- a/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs
+++ b/src/Umbraco.Web/Trees/ContentTreeControllerBase.cs
@@ -131,7 +131,7 @@ namespace Umbraco.Web.Trees
                 var idEntity = GetEntityFromId(id);
                 if (idEntity == null)
                 {
-                    throw new EntityNotFoundException(id, "The passed id doesn't exist");
+                    throw new HttpResponseException(HttpStatusCode.NotFound);
                 }
                 iid = idEntity.Id;
             }
@@ -323,7 +323,7 @@ namespace Umbraco.Web.Trees
             }
             else
             {
-                throw new InvalidCastException("Id must be either an integer or a Guid");
+                return null;
             }
 
             return entity;