C# ASP.NET 注册页将不再更新数据库

>我的注册页面(VS 2015 上的 C# ASP.NET(更新了我的 SQL Server 数据库中的一些条目，然后我更改了数据库，更新了代码(更新web.config字符串等(，现在它只显示此错误：

错误：System.Data.SqlClient.SqlException (0x80131904(：字符串或二进制数据将被截断。该语句已终止。at System.Data.SqlClient.SqlConnection.OnError(SqlException exception， Boolean breakConnection， Action 1 wrapCloseInAction) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action 1 wrapCloseInAction( at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj， Boolean callerHasConnectionLock， Boolean asyncClose( at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior， SqlCommand cmdHandler， SqlDataReader dataStream， BulkCopySimpleResultSet bulkCopyHandler， TdsParserStateObject stateObj， Boolean&dataReady( at System.Data.SqlClient.SqlCommand.FinishExecuteReader (SqlDataReader ds， RunBehavior runBehavior， String resetOptionsString( at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior， RunBehavior runBehavior， Boolean returnStream， Boolean async， Int32 timeout， Task& task， Boolean asyncWrite， SqlDataReader ds， Boolean describeParameterEncryptionRequest( at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior，RunBehavior runBehavior， Boolean returnStream， String 方法， TaskCompletionSource 1 completion, Int32 timeout, Task& task, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource 1 completion， String methodName， Boolean sendToPipe， Int32 timeout， Boolean asyncWrite( at System.Data.SqlClient.SqlCommand.ExecuteNonQuery(( at Registration.Button1_Click(Object sender， EventArgs e( in c：''Users''718358''Documents''Visual Studio 2015''WebSites''Registration2''Registration.aspx.cs：line 61 ClientConnectionId：d0e00199-8bf8-435b-a2ea-03d6f5c8dc40 错误号：8152，状态：13，类：16 注册

这是我的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;
public partial class Registration : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        this.UnobtrusiveValidationMode = System.Web.UI.UnobtrusiveValidationMode.None;
        if (IsPostBack)
        {
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RegistrationDatabaseConnectionString"].ConnectionString);
            conn.Open();
            string checkuser = "SELECT count(*) FROM Customers WHERE CustUserName='" + txtCustUserName.Text + "'";
            SqlCommand com = new SqlCommand(checkuser, conn);
            int temp = Convert.ToInt32(com.ExecuteScalar().ToString());
            if (temp == 1)
            {
                Response.Write("User already exists");
            }
            conn.Close();
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RegistrationDatabaseConnectionString"].ConnectionString);
            conn.Open();
            string insertQuery = "INSERT into Customers (CustUserName, CustPassword, CustFirstName, CustLastName, CustAddress, CustCity, CustProv, CustPostal, CustCountry, CustHomePhone, CustBusPhone, CustEmail) values (@custUsername ,@custPassword ,@custFirstName ,@custLastName ,@custAddress ,@custCity ,@custProv ,@custPostal, @custCountry ,@custHomePhone ,@custBusPhone ,@custEmail)";
            SqlCommand com = new SqlCommand(insertQuery, conn);
            com.Parameters.AddWithValue("@custUsername", txtCustUserName.Text);
            com.Parameters.AddWithValue("@custPassword", txtCustPassword.Text);
            com.Parameters.AddWithValue("@custFirstName", txtCustFirstName.Text);
            com.Parameters.AddWithValue("@custLastName", txtCustLastName.Text);
            com.Parameters.AddWithValue("@custAddress", txtCustAddress.Text);
            com.Parameters.AddWithValue("@custCity", txtCustCity.Text);
            com.Parameters.AddWithValue("@custProv", txtCustProv.Text);
            com.Parameters.AddWithValue("@custPostal", txtCustPostal.Text);
            com.Parameters.AddWithValue("@custCountry", txtCustCountry.Text);
            com.Parameters.AddWithValue("@custHomePhone", txtCustHomePhone.Text);
            com.Parameters.AddWithValue("@custBusPhone", txtCustBusPhone.Text);
            com.Parameters.AddWithValue("@custEmail", txtCustEmail.Text);
            com.ExecuteNonQuery();
            Response.Redirect("Manager.aspx");
            Response.Write("Registration is successful" );
            conn.Close();
        }
        catch(Exception ex)
        {
            Response.Write("Error:"+ex.ToString());
        }
    }
}

谢谢。