R2 2018 (Version number: 2018.2.516)
All known regression issues in this release are fixed in R2 2018 SP1.
Common
The jQuery version that is embedded in the Telerik.Web.UI.dll assembly is upgraded to 3.3.1.
This is done to improve stability, compatibility with modern browsers and security, as well as optimize by dropping support for browsers like IE7 and IE8 that the UI for ASP.NET AJAX suite has not been supporting for years. This upgrade will allow the controls to stay up to date with modern web development and current standards.
This change applies to the window.$telerik.$
variable and to the global jQuery references only if you manually populate them through code similar to window.$ = $telerik.$;
or if you have the following script reference <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.jQueryInclude.js" />
You may find useful the migration guide provided by jQuery: https://jquery.com/upgrade-guide/3.0/.
If you want to use a different version of jQuery (including downgrade to version 1.11.1), follow the Disabling the Embedded jQuery article.
If you get errors like access to strict mode caller function is censored especially under Firefox, the solution is to downgrade to jQuery 1.11.1 that the suite used before. Below is some sample markup.
You can open a support ticket and get a build of R2 2018 that has jQuery 1.12.4 in it instead of 3.3.1. You can use it to test whether it resolves the issues you are facing, as this will be the official solution that will be available in R2 2018 SP1.
How to disable the built-in jQuery 3.3.1 and use 1.11.1:
Here follows a list of the known issues caused by jQuery3
RadAjaxPanel
jQuery button click in RadAjaxPanel under FireFox causes TypeError: access to strict mode caller function is censored. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
RadAutoCompleteBox
Dropdown extends to the left and screen boundary detection to the left does not work in R2 2018. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
RadDropDownList
Cannot postback under Firefox, TypeError: access to strict mode caller function is censored is thrown. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
RadFileExplorer
Cannot rename files under Firefox, TypeError: access to strict mode caller function is censored is thrown. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
Cannot upload files under Firefox, TypeError: access to strict mode caller function is censored is thrown. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
RadListBox
Server events are not raised under Firefox (selection, reorder, transfer, drag-and-drop, etc.), TypeError: access to strict mode caller function is censored is thrown. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
RadSearchBox
Cannot fire OnSearch under Firefox, TypeError: access to strict mode caller function is censored is thrown. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
RadWizard
Cannot change step with a postback under Firefox , TypeError: access to strict mode caller function is censored is thrown. This is caused by the 'use strict' that jQuery 3 begins with. Fixed in R2 2018 SP1.
Other known issues in this release
TypeScript Definitions
The .ts definitions file is wrong in the initial release and does not contain the actual definitions. You can find the file at the bottom of this post. Fixed in R2 2018 SP1.