[Exception] Collection was modified; enumeration operation may not execute

Solution : replace for each loop to standard loop

 

            ArrayList items = new ArrayList();
           
            //foreach (var item in items)
            //{
            //    //do something
            //}                

            for (int i = 0; i < items.Count; i++)
            {
                //do something
            }

Referece: http://alitarhini.wordpress.com/2011/04/06/collection-was-modified-enumeration-operation-may-not-execute/