This is by no way a Database error, this is a front-end error. And since you did not bother to tell what the front-end is, I am taking a shot in the dark. I am assuming that this is a .NET web app.
It seems you have an array n long and you are trying to access the nth or greater element within it. Indexes are 0 based and so an n sized array must be accessed by indexes 0 to n-1
Talk with your front-end developer and have then investigate.