UnauthorizedAccessException was unhandled by user code in SharePoint event receiver

In this article we will be seeing how to resolve “UnauthorizedAccessException was unhandled by user code” in SharePoint event receiver.

In this article we will be seeing how to resolve "UnauthorizedAccessException was unhandled by user code" in SharePoint event receiver.

I had one custom list "MyList" which contains two columns "Title" and "Service Account".

I had one group with Full control "Service Team". In the "Service Account" column I need to add all the users from the "Service Team" group.
I have written ItemAdded event receiver for adding the users from the "Service Team" group to the "Service Account" column.

public override void ItemAdded(SPItemEventProperties properties)
       {
           base.ItemAdded(properties);
           SPSecurity.RunWithElevatedPrivileges(delegate()
           {
               SPWeb web = properties.Web;
               SPListItem item = properties.ListItem;
               SPGroup group = web.Groups["Service Team"];
               web.AllowUnsafeUpdates = true;
               SPFieldUserValueCollection UserCollection = new SPFieldUserValueCollection();
               foreach (SPUser user in group.Users)
               {
                   SPFieldUserValue UserName = new SPFieldUserValue(web, user.ID, user.LoginName);
                   UserCollection.Add(UserName);
               }
               item["Service Account"] = UserCollection;
               item.Update();        
           });
       }

When the user with contribute access tried to add the column, users from the "Service Team" were not added to the column and I was getting the following error when I was debugging.



Even though I was using SPSecurity.RunWithElevatedPrivileges I was getting the error. That is because "when using SPSecurity.RunWithElevatedPrivileges, we need to open an elevated site context through a new SPSite object in order to really be elevated". Then I tried with the following code which added users to the columns successfully.

public override void ItemAdded(SPItemEventProperties properties)
       {
           base.ItemAdded(properties);
           SPSecurity.RunWithElevatedPrivileges(delegate()
           {
               using(SPSite site=new SPSite (properties.SiteId))
                {
                    using (SPWeb web = site.RootWeb)
                    {                       
                        SPListItem item = properties.ListItem;
                        SPGroup group = web.Groups["Service Team"];
                        web.AllowUnsafeUpdates = true;
                        SPFieldUserValueCollection UserCollection = new SPFieldUserValueCollection();
                        foreach (SPUser user in group.Users)
                        {
                            SPFieldUserValue UserName = new SPFieldUserValue(web, user.ID, user.LoginName);
                            UserCollection.Add(UserName);
                        }
                        item["Service Account"] = UserCollection;
                        item.Update();
                    }
                }
           });
       }