A network-related or instance-specific error occurred while establishing a connection to SQL Server. Error Locating Server/Instance Specified)

Question

Moving a web project from test enviroment to the web server made this error occur whenever tehre\'s an attempt to open a connection to the sql server.

We can insert

Answer 1

causes this error is connectionString in webConfig
Set connectionString in webConfig.
name of connectionStrin in webConfig and code behind must be same.

in web.config:

<configuration>
<connectionStrings>
    <add name="DSVUShort" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
</connectionStrings>
<system.web>
    <compilation debug="true" targetFramework="4.0"/>
</system.web>

in code:

SqlConnection Connection = new SqlConnection(ConfigurationManager.ConnectionStrings["DSVUShort"].ToString());  
Connection.Open();