I have a .Net 4.0 site that uses Entity Framework and Linq to SQL. After reworking a few tables and a few page operations, a new error appeared: "Row not found or changed". Every time I commit changes to a particular table, this error would be raised. From a quick review of msdn and the internet, the primary reason for this exception appears to be data concurrency issues - (The source data in the database is out of sync with the data you are attempting to update.) That did not apply to my development ......