GridView fired event wasn't handled

Question

Basically , the table that i am going to fetch has around 60 rows and i want to display in gridview by giving allowpaging & allowsorting property as 'true and also pagesize as '4'. It didn't give any complie time or runtime error but as soon when i click on the attribute for sorting or paging , it will throw an error. So, how can i overcome this exception...!!!!

 

 

Error: 

The GridView 'grdview' fired event PageIndexChanging which wasn't handled.

The GridView 'grdview' fired event Sorting which wasn't handled.

<asp:GridView ID="grdview" CssClass="table table-hover" AllowPaging="true" PageSize="4" AllowSorting="true" runat="server"></asp:GridView>