类型为“ System.Data.SqlClient.SqlException”的异常实例失败

Question

I'm a beginner with C# and I'm working with a web service. When I tried to test my service, this error message occurs:

An exception of type 'System.InvalidOperationException' occurred in System.Data.dll but was not handled in user code

Additional information: Instance failure.

Here is my connection string in web configuration:

<connectionStrings>
    <add name="connection" 
         connectionString="Data Source=DESKTOP-CIRUCVV\\SQLEXPRESS;Initial Catalog=CustomerManagerment;Integrated Security=True;"/>
</connectionStrings>

Here is my code inside the web service class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Data.SqlClient;
using System.Data;
using System.Web.Configuration;

namespace WebService
{
    /// <summary>
    /// Summary description for CustomerService
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
    // [System.Web.Script.Services.ScriptService]
    public class CustomerService : System.Web.Services.WebService
    {
        static string strcon = WebConfigurationManager.ConnectionStrings["connection"].ConnectionString;

        public CustomerService() { }

        [WebMethod(Description = "Show Customers")]
        public DataSet showCustomer() 
        {
            SqlConnection con = new SqlConnection(strcon);
            string Sql = "select * from Customers";

            SqlDataAdapter da = new SqlDataAdapter(Sql, con);
            DataSet ds = new DataSet();
            da.Fill(ds);

            return ds;
        }
    }
}

Answer 1

将DESKTOP-CIRUCVV\\\\SQLEXPRESS更改为DESKTOP-CIRUCVV\\SQLEXPRESS