If you are receiving this application error message from your web application. The solution is to modify your application's web.config file and add the following line to the connection string element:
<connectionStrings>
<remove name="LocalSqlServer" />
<add name="LocalSqlServer" connectionString="Data Source=DBServerName;Integrated Security=false;Initial Catalog=DBName;User ID=DBLogin;Password=DBPassword" providerName="System.Data.SqlClient" />
</connectionStrings>
Please be sure that you add the correct values for the connection string. Log into your control panel and review your database information.