connectionStrings add name="ConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Update.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient" connectionStrings the closing and opening braces are there. i have personally removed here. i'm also getting the same error. above is my code. please check it whether it's correct or not. on my system it's working fine. but when i upload my website to the webserver (internet) it gave this error. can u tell me it's a problem with my coding or the webserver side problem. thanks.