diff --git a/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeRepositoryBase.cs b/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeRepositoryBase.cs
index aa32995e03..560a8ffdad 100644
--- a/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeRepositoryBase.cs
+++ b/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeRepositoryBase.cs
@@ -175,7 +175,7 @@ AND umbracoNode.nodeObjectType = @objectType",
             }
 
             //Insert Tabs
-            foreach (var propertyGroup in entity.PropertyGroups.OrderBy(g => g.Level))
+            foreach (var propertyGroup in entity.PropertyGroups.OrderBy(x => x.Level).ToArray())
             {
                 var tabDto = PropertyGroupFactory.BuildGroupDto(propertyGroup, nodeDto.NodeId);
                 var primaryKey = Convert.ToInt32(Database.Insert(tabDto));
@@ -374,7 +374,7 @@ AND umbracoNode.id <> @id",
             }
 
             // insert or update groups, assign properties
-            foreach (var propertyGroup in entity.PropertyGroups.OrderBy(x => x.Level))
+            foreach (var propertyGroup in entity.PropertyGroups.OrderBy(x => x.Level).ToArray())
             {
                 // insert or update group
                 var groupDto = PropertyGroupFactory.BuildGroupDto(propertyGroup, entity.Id);
diff --git a/src/Umbraco.Web/Models/Mapping/PropertyTypeGroupMapper.cs b/src/Umbraco.Web/Models/Mapping/PropertyTypeGroupMapper.cs
index 122ade015c..90ee756f01 100644
--- a/src/Umbraco.Web/Models/Mapping/PropertyTypeGroupMapper.cs
+++ b/src/Umbraco.Web/Models/Mapping/PropertyTypeGroupMapper.cs
@@ -200,7 +200,7 @@ namespace Umbraco.Web.Models.Mapping
                 group.ParentTabContentTypeNames = parentGroups.SelectMany(x => x.ParentTabContentTypeNames).ToArray();
             }
 
-            return groups.OrderBy(x => x.Level).ThenBy(x => x.SortOrder);
+            return groups.OrderBy(x => x.Level).ThenBy(x => x.SortOrder).ToArray();
         }
 
         private IEnumerable<TPropertyType> MapProperties(IEnumerable<PropertyType> properties, IContentTypeBase contentType, int groupId, bool inherited)