IE8 results in "Error: 'JSON' is undefined"

5 posts, 1 answers
  1. Dave
    Dave avatar
    26 posts
    Member since:
    Aug 2012

    Posted 26 Dec 2010 Link to this post

    Hi there,

    We end up with an error "Error: 'JSON' is undefined" when accessing pages using telerik controls in IE8.
    It is quite new when migrating to IE8 (after some security hotfix?) and the compatibility mode does not help...
    Trying the last version of Telerik controls does not help neither...

    Do someone face similar issue and can give us some hint there?

  2. Answer
    Lini avatar
    2144 posts

    Posted 28 Dec 2010 Link to this post

    Hello David,

    Does the problem happen with all Telerik controls or only with certain ones? Does the problem happen on pages where there are no RadControls visible (e.g. only RadScriptManager)? Are you using a <meta> tag to force IE to a specific mode or is it running in the default (IE 8) mode?

    The only reference I could find to a 'JSON' keyword in our code is in the jQuery version we are using and even there it is properly checked before it is used. This means that the problem might be caused by another library
    or client code you have on your site. Check the JavaScript code you have for "JSON" (match whole word, match case) and see if you have any references that are not used properly.

    the Telerik team
    Browse the vast support resources we have to jump start your development with RadControls for ASP.NET AJAX. See how to integrate our AJAX controls seamlessly in SharePoint 2007/2010 visiting our common SharePoint portal.
  3. Dave
    Dave avatar
    26 posts
    Member since:
    Aug 2012

    Posted 02 Jan 2011 Link to this post


    It was an external wrong piece of code from another framework that was buggy when testing locally.
    Thank you having helped us pin-point the issue.

    Best Regards,
  4. Rafael
    Rafael avatar
    8 posts
    Member since:
    Dec 2007

    Posted 03 Feb 2011 Link to this post


    I was looking at this post because I had the same problem (JSON undefined) with my pages in IE8. The page is very simple, a Telerik Web Form as it comes from the “Add Rad Control scenario…” wizard.

    The problem only occurs when IE is in Compatibility view. If I deactivate this feature all seems to work fine.

    I hope this help other people with the same problem.


  5. Shirish
    Shirish avatar
    12 posts
    Member since:
    Jan 2013

    Posted 12 Jul 2018 in reply to Rafael Link to this post


    Also consider adding this after <title></title>
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    I was able to fixed the issue after adding this.
    Hope this helps.

    Shirish Bhavthankar

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