This error took me a while to figure out. I was using SqlDataSource with stored procedures for SELECT and UPDATE commands. The SELECT worked fine. Then I added UPDATE command and while trying to update, I would get this error: "Procedure of function has too many arguments specified" Apparently, good guys at .NET decided it is necessary to send SELECT parameters with the UPDATE command as well. So when I was sending the required parameters to the UPDATE sp, in reality, it was also getting my SELECT...