Error updating Sharepoint List item, when called from web service

I'm using ajax to call a webservice which updates a sharepoint list.

It works when I call the code from unit tests, but running the code in a browser causes an exception:

System.InvalidOperationException: Operation is not valid due to the current state of the object. at Microsoft.SharePoint.WebControls.SPControl.SPWebEnsureSPControl(HttpContext context) at Microsoft.SharePoint.WebControls.SPControl.GetContextWeb(HttpContext context) at Microsoft.SharePoint.SPContext.get_Current() at Microsoft.SharePoint.SPListItem.AddOrUpdateItem(Boolean bAdd, Boolean bSystem, Boolean bPreserveItemVersion, Boolean bNoVersion, Boolean bMigration, Boolean bPublish, Boolean bCheckOut, Boolean bCheckin, Guid newGuidOnAdd, Int32& ulID, Object& objAttachmentNames, Object& objAttachmentContents, Boolean suppressAfterEvents) at Microsoft.SharePoint.SPListItem.UpdateInternal(Boolean bSystem, Boolean bPreserveItemVersion, Guid newGuidOnAdd, Boolean bMigration, Boolean bPublish, Boolean bNoVersion, Boolean bCheckOut, Boolean bCheckin, Boolean suppressAfterEvents) at Microsoft.SharePoint.SPListItem.Update()

My code to update the list item is:

SPSecurity.RunWithElevatedPrivileges(delegate()
        {
            using (SPSite site = new SPSite(siteURL))
            {
                using (SPWeb web = site.OpenWeb(path))
                {
                    SPList userProfile = web.Lists[userList];
                    SPQuery qry = new SPQuery
                    {
                        Query =
                            "<Where><Eq><FieldRef Name='Title' /><Value Type='Text'>" +
                            accountName +
                            "</Value></Eq></Where><ViewFields><FieldRef Name='ID' /><FieldRef Name='Title' /><FieldRef Name='LastUpdated' /><FieldRef Name='Reaso开发者_开发技巧n' /></ViewFields>"
                    };

                    SPListItemCollection spListItemCollection = userProfile.GetItems(qry);

                    if (spListItemCollection.Count == 1)
                    {
                        //edit user
                        SPListItem item = spListItemCollection[0];
                        item["Updated"] = DateTime.Now;
                        item["Reason"] = updateReason;
                        item.Update();
                    }
                }
            }
        });

It errors on item.Update();

Try adding this:

HttpContext context = HttpContext.Current;
if (HttpContext.Current != null)
{
    if (context.Items["HttpHandlerSPWeb"] == null)
        context.Items["HttpHandlerSPWeb"] = site.RootWeb;
    if (context.Items["Microsoft.Office.ServerContext"] == null)
        context.Items["Microsoft.Office.ServerContext"] = ServerContext.GetContext(site);
}

The problem was with security. The following line needs to be added (although not ideal)

web.AllowUnsafeUpdates = true;

I also removed the line

SPSecurity.RunWithElevatedPrivileges(delegate()

and changed the SPSite and SPWeb to not use "using".