object reference not set to an instance of an object.

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 
Line 34:         }
Line 35: 
Line 36:         string strcon = ConfigurationManager.AppSettings["payrollConnectionString"].ToString();
Line 37:         protected void Page_Load(object sender, EventArgs e)
Line 38:         {

Source File: C:\Users\Surya\Documents\Visual Studio 2008\Projects\Surya\imageexport\imageexport\Default.aspx.cs    Line: 36 

[NullReferenceException: Object reference not set to an instance of an object.]
   imageexport._Default..ctor() in C:\Users\Surya\Documents\Visual Studio 2008\Projects\Surya\imageexport\imageexport\Default.aspx.cs:36
   ASP.default_aspx..ctor() in c:\Users\Surya\AppData\Local\Temp\Temporary ASP.NET Files\root\d163ef2f\853db724\App_Web_s6dguo8s.0.cs:0
   __ASP.FastObjectFactory_app_web_s6dguo8s.Create_ASP_default_aspx() in c:\Users\Surya\AppData\Local\Temp\Temporary ASP.NET Files\root\d163ef2f\853db724\App_Web_s6dguo8s.2.cs:0
   System.Web.Compilation.BuildResultCompiledType.CreateInstance() +32
   System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert) +119
   System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) +33
   System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) +40
   System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig) +160
   System.Web.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +93
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

namespace imageexport
{
    public partial class _Default : System.Web.UI.Page
    {
        class Problem
        {
            static void Main()
            {
                Problem problem = null; // problem has not been instantiated
                // ...
            }

            public int ProblemProperty
            {
                get { return 0; }
            }

            public string ProblemMethod()
            {
                return null;
            }
        }

        string strcon = ConfigurationManager.AppSettings["payrollConnectionString"].ToString();
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindGridData();
            }

        }
        protected void btnUpload_Click(object sender, EventArgs e)
        {
            //Condition to check if the file uploaded or not
            if (fileuploadImage.HasFile)
            {
                //getting length of uploaded file
                int length = fileuploadImage.PostedFile.ContentLength;
                //create a byte array to store the binary image data
                byte[] imgbyte = new byte[length];
                //store the currently selected file in memeory
                HttpPostedFile img = fileuploadImage.PostedFile;
                //set the binary data
                img.InputStream.Read(imgbyte, 0, length);
                string imagename = txtImageName.Text;
                //use the web.config to store the connection string
                SqlConnection connection = new SqlConnection(strcon);
                connection.Open();
                SqlCommand cmd = new SqlCommand("INSERT INTO Image (ImageName,Image) VALUES (@imagename,@imagedata)", connection);
                cmd.Parameters.Add("@imagename", SqlDbType.VarChar, 50).Value = imagename;
                cmd.Parameters.Add("@imagedata", SqlDbType.Image).Value = imgbyte;
                int count = cmd.ExecuteNonQuery();
                connection.Close();
                if (count == 1)
                {
                    BindGridData();
                    txtImageName.Text = string.Empty;
                    ScriptManager.RegisterStartupScript(this, this.GetType(), "alertmessage", "javascript:alert('" + imagename + " image inserted successfully')", true);
                }
            }
        }
        /// <summary>
        /// function is used to bind gridview
        /// </summary>
        private void BindGridData()
        {
            SqlConnection connection = new SqlConnection(strcon);
            SqlCommand command = new SqlCommand("SELECT imagename,ImageID from [Image]", connection);
            SqlDataAdapter daimages = new SqlDataAdapter(command);
            DataTable dt = new DataTable();
            daimages.Fill(dt);
            gvImages.DataSource = dt;
            gvImages.DataBind();
            gvImages.Attributes.Add("bordercolor", "black");
        }
    }
}

namespace imageexport
{
    public partial class _Default : System.Web.UI.Page
    {
        class Problem
        {
            static void Main()
            {
                Problem problem = null; // problem has not been instantiated
                // ...
            }

            public int ProblemProperty
            {
                get { return 0; }
            }

            public string ProblemMethod()
            {
                return null;
            }
        }

        string strcon = ConfigurationManager.AppSettings["payrollConnectionString"].ToString();
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindGridData();
            }

        }
        protected void btnUpload_Click(object sender, EventArgs e)
        {
            //Condition to check if the file uploaded or not
            if (fileuploadImage.HasFile)
            {
                //getting length of uploaded file
                int length = fileuploadImage.PostedFile.ContentLength;
                //create a byte array to store the binary image data
                byte[] imgbyte = new byte[length];
                //store the currently selected file in memeory
                HttpPostedFile img = fileuploadImage.PostedFile;
                //set the binary data
                img.InputStream.Read(imgbyte, 0, length);
                string imagename = txtImageName.Text;
                //use the web.config to store the connection string
                SqlConnection connection = new SqlConnection(strcon);
                connection.Open();
                SqlCommand cmd = new SqlCommand("INSERT INTO Image (ImageName,Image) VALUES (@imagename,@imagedata)", connection);
                cmd.Parameters.Add("@imagename", SqlDbType.VarChar, 50).Value = imagename;
                cmd.Parameters.Add("@imagedata", SqlDbType.Image).Value = imgbyte;
                int count = cmd.ExecuteNonQuery();
                connection.Close();
                if (count == 1)
                {
                    BindGridData();
                    txtImageName.Text = string.Empty;
                    ScriptManager.RegisterStartupScript(this, this.GetType(), "alertmessage", "javascript:alert('" + imagename + " image inserted successfully')", true);
                }
            }
        }
        /// <summary>
        /// function is used to bind gridview
        /// </summary>
        private void BindGridData()
        {
            SqlConnection connection = new SqlConnection(strcon);
            SqlCommand command = new SqlCommand("SELECT imagename,ImageID from [Image]", connection);
            SqlDataAdapter daimages = new SqlDataAdapter(command);
            DataTable dt = new DataTable();
            daimages.Fill(dt);
            gvImages.DataSource = dt;
            gvImages.DataBind();
            gvImages.Attributes.Add("bordercolor", "black");
        }
    }
}