Fix RadSpell Styles with Cookieless Sessions

Updated on Oct 27, 2026

Environment

Product	UI for ASP.NET AJAX
Version	2026.3.812

Description

After upgrading to UI for ASP.NET AJAX 2026.3.812, the RadSpell dialog can render without its styles. The dialog content may show wide buttons or unexpected list markers while the surrounding page remains styled.

Cause/Possible Cause(s)

The RadSpell dialog loads its stylesheets through Telerik.Web.UI.WebResource.axd. With ASP.NET cookieless session state, the request can be redirected to a session-enabled handler URL that does not contain the session identifier. The stylesheet is not returned, so the dialog content is unstyled.

Solution

Enable the Telerik CDN for stylesheets in web.config:

xml

<appSettings>
    <add key="Telerik.StyleSheetManager.TelerikCdn" value="Enabled" />
</appSettings>

This makes the RadSpell dialog load its stylesheets from the Telerik CDN instead of the local resource handler. The setting must be in web.config; a RadStyleSheetManager declared on the page does not configure the separate dialog page.

If the application cannot reach the Telerik CDN, host the required stylesheets and set the CDN base URLs in web.config:

xml

<appSettings>
    <add key="Telerik.StyleSheetManager.TelerikCdn.BaseUrl" value="http://your-server-url/" />
    <add key="Telerik.StyleSheetManager.TelerikCdn.BaseSecureUrl" value="https://your-server-url/" />
</appSettings>

When possible, changing the application to cookie-based session state also prevents the redirect:

xml

<sessionState cookieless="UseCookies" />

Notes

Verify that requests for Telerik.Web.UI.WebResource.axd return the stylesheet content instead of a redirect. Keep the patched product version; reverting to an older version is not required.

See Also

• RadSpell overview
• RadStyleSheetManager overview
• Using Telerik CDN