Buffering error when uplaod documents

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C#

ASP.NET

At the time of uploading Documents it uploaded properly at locally on machine but when i am checking it on server side same functionality first upload documents & Click on Add Button at the time it will buffer long time. i was checked error log file in that it was generated error on this line
protected void ErrorMsg_ServerValidate(object source, ServerValidateEventArgs args)

{

//on this line error occure when checking on server side
   string fileName = Functions.ToString(fileUpload.PostedFile.FileName);
        ErrorMsg.Text = "";
        if (fileUpload.Value != "")
        {
            pGotFile = true;
            pFileExt = GetExtension(fileUpload.PostedFile.FileName).ToLower();
            pFilePost = fileUpload.PostedFile;
            if (pFileExt == ".pdf")
            {
                Ind = true;
            }

            if (!Ind)
            {
                args.IsValid = false;
                ErrorMsg.Text = "The file format you specified is not supported";
               return;
            }

            if (fileUpload.PostedFile.ContentLength >= Functions.ToInt32(Config.Get("SplitterDocUploadValidationSize")))
            {
                args.IsValid = false;
                ErrorMsg.Text = Functions.ToString(Config.Get("SplitterDocUploadValidationMessage"));
                return;
            }
            if (string.IsNullOrEmpty(fileName))
            {
                fileName = System.IO.Path.GetFileName(fileUpload.PostedFile.FileName);
            }
            else
            {
                fileName = fileName + pFileExt;
            }

        }
        else
        {
            pGotFile = false;
            if (pRequired)
            {
                args.IsValid = false;
                ErrorMsg.Text = "Please select the document to upload";
            }
        }
    }

its work fine on local machine but on server side it was just buffered long time .
idea on that suggest.