Web API，Web Service SharePoint对象操作报Operation is not valid due to the current state of the object解决方案

Web API，Web Service SharePoint对象操作报Operation is not valid due to the current state of the object解决方案，这是因为当前的user信息不一致导致的，添加HttpContext.Current = null;，解决，要类似这样：

SPSecurity.RunWithElevatedPrivileges(delegate()
            {
                HttpContext.Current = null;
                using (SPSite site = new SPSite(targetWeb))
                {
                    using (SPWeb web = site.OpenWeb())
                    {
                        SPList targetlist = web.Lists[targetList];
                        foreach (ItemType item in import.item)
                        {
   ...
                        }
                    }
                }
            });