Obscure error in Site.Master

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ASP.NET

I am getting on obscure error in Site.Master:

Compiler Error Message: CS0426: The type name 'SiteMaster' does not exist in the type 'System.Web.UI.WebControls.FileUpload'

Source Error:        }
Line 173:        
Line 174:        [TemplateContainer(typeof(FileUpload.SiteMaster))]
Line 175:        [TemplateInstanceAttribute(System.Web.UI.TemplateInstance.Single)]
Line 176:        public virtual System.Web.UI.ITemplate Template_HeadContent {

My code does not go to Line 173 where the error is.
Here is my code:

if (FileUpload1.HasFile)
{
   try
   {
      string filename = System.IO.Path.GetFileName(FileUpload1.FileName);
      string path = System.IO.Path.GetFullPath(FileUpload1.FileName);
      string path1 = System.IO.Path.GetDirectoryName(FileUpload1.FileName);
      string path2 = System.IO.Path.GetExtension(FileUpload1.FileName);
      TextBox2.Text = filename;
      TextBox3.Text = path;
      TextBox4.Text = path1;
      TextBox5.Text = path2;
   }
   catch (Exception ex)
   {
      TextBox1.Text = ex.ToString();
   }
}