WebResource.axd Error - "handler must be registered"

In some cases in appears due to corrupt installation of asp.net 4. Just add this

<system.webServer>
   <handlers>
      <add name="WebResource.axd" type="System.Web.Handlers.AssemblyResourceLoader" path="WebResource.axd" verb="GET,HEAD,POST,DEBUG" />
   </handlers>
</system.webServer>

Off you go!

How to check a Constraint Exception in ASP.net (C#)

try

            {

                //statements

            }

            catch (ConstraintException cex)

            {

                throw;

            }

            catch (Exception ex)

            {

                throw;

            }

            /*

             * order matters

            */

jQuery Countdown Timer

A jQuery plugin that sets a div or span to show a countdown to a given time.

Usage

1. Include the jQuery library in the head section of your page.

   <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script>

2. Download and include the jQuery Countdown CSS and JavaScript in the head section of your page.

   <style type="text/css">@import "jquery.countdown.css";</style> 
   <script type="text/javascript" src="jquery.countdown.js"></script>

   Alternately, you can use the packed version jquery.countdown.pack.js (10.0K vs 30.1K), or the minified version jquery.countdown.min.js (12.6K, 4.3K when zipped).
3. Connect the countdown functionality to your divs.

   $(selector).countdown({until: liftoffTime});

   You can include custom settings as part of this process.

   $(selector).countdown({until: liftoffTime, format: 'dHM'});

WebService: Request format is unrecognized for URL unexpectedly ending in {/MethodName}

All you need is to add the following to your web.config

<webServices>
     <protocols>
          <add name="HttpGet" />
          <add name="HttpPost" />
     </protocols>

</webServices>

and call the service this way

<script type="text/javascript">
$.ajax({
       type: "POST",
       url: "CatsService.asmx/GetCatsByID",
       data: "{id: " + li.attr("rel") + " }",
       contentType: "application/json; charset=utf-8",
       dataType: "json",
       success: function (o) {
           o = o.d;
           for (var i = 0; i < o.length; i++) {
           $('ul').append('<li><a href="javascript:void(0)">' + o[i].title + '</a></li>');
           }
       }
});
</script>

All is done

Crystal Report Displaying Blank or Empty Page Without Any Errors

You created a lot of reports with crystal reports and everything was fine until you uploaded online. You get no error just a blank page with nothing on it. What has gone wrong, "Is it because there are no records in table", you ask yourself.
Well I myself got stuck with this error few days ago, so i created a blank report with just a custom static text in it, but nothing showed up. After a lot of searching I found out that it was because of a missing folder named "aspnet_client" which must be present in order for crystal reports to work properly.

So I copied this folder from c:/inetpub/wwwroot/aspnet_client into my website and voilà it worked.

and for dot net framework 4.6 just copy existing framework folder in aspnet_client\system_web folder and the rename it to 4_81 or what ever version is installed on your system and your are done

To check your version click here
http://w3dproblems.dcense.com/2015/09/what-net-version-are-you-running-20-45.html