Intermittent failure of captcha image to appear

2 posts, 0 answers
  1. Paul Robertson
    Paul Robertson avatar
    78 posts
    Member since:
    May 2010

    Posted 10 Jan 2013 Link to this post

    Hi there

    I have a consistent but intermittent (maybe 50:50) problem with the image for a radCaptcha control not being displayed, showing instead only the grey box on the occasions that the rendering fails. I know about using the HttpHandlerUrl property to explicitly provide the location of Telerik.Web.UI.axd, and the fact that the image is loaded from the Cache by default, so I am wondering if this is some issue with a cache management conflict caused by some other javascript functions I am running on page load?

    Could anybody point me in a good direction about how to troubleshoot this issue, as I have run out of ideas! Is there any client-side API for radCaptcha that might allow me to examine what is going on with the captcha control as the client side script runs? Failing that, is there a recommended location for setting the HttpHandlerUrl property back at the server-side processing? I have tried the init handlers for both the page and the control itself, but nothing makes any difference to the problem.

    Thanks if you can advise

  2. Slav
    Slav avatar
    1359 posts

    Posted 11 Jan 2013 Link to this post

    Hello Paul,

    The RadCaptcha renders grey image when the image with the validation code cannot be found in cache/session. This could be a result of:
     - Using RadCaptcha in a WebFarm/WebGarden Environment;
     - The cache in you website being cleared for some reason. You could check if this is the case by storing some values in Cache and retrieving them.
     - The life cycle of the page, in which the captcha is placed, is executed more than once due to the reason described in this blog post.

    Kind regards,
    the Telerik team
    If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed now.
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