What's new

UI for ASP.NET AJAX

Release History

Telerik UI for ASP.NET AJAX 2026.3.812 (2026 Q3)

August 12, 2026

Security

FIXED
  • Ongoing security improvements

Common

NEW
  • Added the Telerik.Web.UI.FileBrowserAllowedPaths web.config setting to restrict the folders accessible to RadEditor and RadFileExplorer's file browser dialogs
  • Added the Telerik.PersistenceFramework.AllowedCustomTypes web.config setting to allow custom types used with the Persistence Framework (e.g. RadDock, RadGrid, RadPivotGrid state persistence)
  • Added the Telerik.Web.UI.AllowedCustomDialogTypes web.config setting to allow custom dialog types used with RadEditor dialogs during deserialization
  • The Telerik.Upload.AllowedCustomMetaDataTypes, Telerik.Web.UI.AllowedCustomDialogTypes, and Telerik.PersistenceFramework.AllowedCustomTypes web.config settings now accept fully-qualified assembly names (FQAN), improving custom type resolution in Web Forms Site projects compiled on the fly
FIXED
  • Watermarks no longer appear on valid trial licenses
Dependencies

AsyncUpload

FIXED
  • e.UploadResult in the FileUploadEvent throws InvalidOperationException: This type is not allowed
  • Disabling session state and csrf causes null reference exception when using async upload

Chart (obsolete)

Breaking Changes
  • RadChart has been removed from the Telerik.Web.UI assembly. Applications that reference RadChart or its related classes must migrate to RadHtmlChart. See migration guidance

MonthYearPicker

FIXED
  • RadMonthYearPicker is not rendered correctly when RenderMode is set to Lightweight in the web.config and TodayButtonCaption is defined

Panelbar

FIXED
  • Accesskey on items not focusing them in PanelBar control

PersistenceFramework

FIXED
  • Error: System.InvalidOperationException: This type is not allowed

Spreadsheet

FIXED
  • A JavaScript error is thrown when typing a font size that is not presented in the dropdown
Breaking Changes
  • The RadSpreadsheet dependency assembly has been renamed from Telerik.Web.Spreadsheet to Telerik.Spreadsheet.Web. Update project references accordingly. Telerik.Spreadsheet.Web is now publicly available as a separate package on NuGet and must be added explicitly: https://www.nuget.org/packages/Telerik.Spreadsheet.Web

UI for ASP.NET AJAX

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