i am getting an error during the execution of the current web request

ASP.NET web forms can only have one server side form tag which can be used on a rendered page. You can have other forms, but they just can't have the runat="server" attribute.

Make sure you don't have two <form runat="server"> tag in your page. And if your page is attached to master page, make sure master should not contain <form runat="server">.

hope it helps :)

only one server-side form tag is allowed on a page. This error occurs if you have two or more server-side form tags on your page.
View source of your page and search for form tag and remove it if its being placed at two locations.
Refer discussion at code project for the same
http://www.codeproject.com/Messages/3171846/A-page-can-have-only-one-server-side-Form-tag.aspx[^]