The ObjectContext instance has been disposed and can no longer be used for operations that require a connection

        public override void Dispose()

        {

            string objectContextKey = "MIP_" + HttpContext.Current.GetHashCode().ToString("x"); if (HttpContext.Current.Items.Contains(objectContextKey))

            {

                SPMIPEntities ctx = HttpContext.Current.Items[objectContextKey] as SPMIPEntities; if (ctx != null)

                {

                    ctx.Dispose(); HttpContext.Current.Items.Remove(objectContextKey);

                }

            }

            base.Dispose();

        }