Value cannot be null.<br>Parameter name: input

Server Error in '/' Application.

Value cannot be null.
Parameter name: input

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.ArgumentNullException: Value cannot be null.
Parameter name: input

Source Error:

Line 43:     protected void Page_Load(object sender, EventArgs e)
Line 44:     {
Line 45:         string strText = Regex.Replace(Request.QueryString["searchtext"], @"<[^>]*>", String.Empty);
Line 46:         string path = Request.QueryString["path"];
Line 47:         cms_sp.Path = path + "/%";

Source File: c:\webspace\\httpdocs\CMSTemplates\DevCms\TimKiem.aspx.cs    Line: 45

Stack Trace:

[ArgumentNullException: Value cannot be null.
Parameter name: input]
   System.Text.RegularExpressions.Regex.Replace(String input, String replacement) +6669490
   System.Text.RegularExpressions.Regex.Replace(String input, String pattern, String replacement) +91
   CMSTemplates_DevCms_TimKiem.Page_Load(Object sender, EventArgs e) in c:\webspace\\httpdocs\CMSTemplates\DevCms\TimKiem.aspx.cs:45
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
   System.Web.UI.Control.OnLoad(EventArgs e) +95
   CMS.UIControls.ContentPage.OnLoad(EventArgs e) +32
   System.Web.UI.Control.LoadRecursive() +59
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +678

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.7.3282.0