diff --git a/app/models/project.rb b/app/models/project.rb
index 8b591a68c..7b9080833 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -431,7 +431,7 @@ class Project < ActiveRecord::Base
       project = project.is_a?(Project) ? project : Project.find(project)
       if project
         # clear unique attributes
-        attributes = project.attributes.dup.except('name', 'identifier', 'id', 'status')
+        attributes = project.attributes.dup.except('id', 'name', 'identifier', 'status', 'parent_id', 'lft', 'rgt')
         copy = Project.new(attributes)
         copy.enabled_modules = project.enabled_modules
         copy.trackers = project.trackers