After banging my head for days on a “A potentially dangerous Request.Form value was detected" issue when post (ajax-ing) a form in ASP.NET MVC 2 on .NET 4.0 framework using jQuery and CKEditor, I found that when you use the following:       Code Snippet   $.ajax({     url: '/TheArea/Root/Add',     type: 'POST',     data: $("#form0Add").serialize(),     dataType: 'json',     //contentType: 'application/json; charset=utf-8',     beforeSend: function ()     {         pageNotify("NotifyMsgContentDiv", "MsgDefaultDiv", '<img src="/Content/images/content/icons/busy.gif" /> Adding post, please wait...', 300, "", true);         $("#btnAddSubmit").val("Please wait...").addClass("button-disabled").attr("disabled", "disabled");     },     success: function (data)     {         $("#btnAddSubmit").val("Add New Post").removeClass("button-disabled").removeAttr('disabled');         redirectToUrl("/Exhibitions");     },     error: function ()     {         pageNotify("NotifyMsgContentDiv", "MsgErrorDiv", '<img src="/Content/images/content/icons/cross.png" /> Could not add post. Please try again or contact your web administrator.', 6000, "normal");         $("#btnAddSubmit").val("Add New Post").removeClass("button-disabled").removeAttr('disabled');     } });         Notice the following:    Code Snippet   data: $("#form0Add").serialize(),         You may run into the “A potentially dangerous Request.Form value was detected" issue with this. One of the requirements was NOT to disable ValidateRequest (ValidateRequest=”false”). For this project (and any other project) I felt it wasn’t necessary to disable ValidateRequest.         Note: I’ve search for alternatives for the posting issue and everyone and their mothers continually suggested to disable ValidateRequest. That bothers me – a LOT. So, disabling ValidateRequest is totally out of the question (and always will be).      So I thought to modify how the “data: “ gets serialized. the ajax data fix was simple, add a .html(). YES!!! IT WORKS!!! No more “potentially dangerous” issue, ajax form posts (and does it beautifully)! So if you’re using jQuery to $.ajax() a form with CKEditor, remember to do:    Code Snippet   data: $("#form0Add").serialize().html(),               or bad things will happen. Also, don’t forget to set     Code Snippet   config.htmlEncodeOutput = true;         for the CKEditor config.js file (or equivalent). Example:    Code Snippet   CKEDITOR.editorConfig = function( config ) {     // Define changes to default configuration here. For example:     // config.language = 'fr';     config.uiColor = '#ccddff';     config.width = 640;     config.ignoreEmptyParagraph = true;     config.resize_enabled = false;     config.skin = 'kama';     config.enterMode = CKEDITOR.ENTER_BR;       config.toolbar = 'MyToolbar';     config.toolbar_MyToolbar =     [         ['Bold', 'Italic', 'Underline'],         ['JustifyLeft', 'JustifyCenter', 'JustifyRight', 'JustifyBlock', 'Font', 'FontSize', 'TextColor', 'BGColor'],         ['BulletedList', 'NumberedList', '-', 'Outdent', 'Indent'],         '/',         ['Scayt', '-', 'Cut', 'Copy', 'Paste', 'Find'],         ['Undo', 'Redo'],         ['Link', 'Unlink', 'Anchor', 'Image', 'Flash', 'HorizontalRule'],         ['Table'],         ['Preview', 'Source']     ];     config.htmlEncodeOutput = true; };         Happy coding!!!  Tags: jQuery ASP.NET MVC 2 ASP.NET 4.0 AJAX