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2026 Releases

Updated on Aug 12, 2026

This article lists the breaking or important changes in the 2026 releases of Telerik UI for ASP.NET Core.

Telerik UI for ASP.NET Core 2026 Q3

New SummarizeAfter behavior for MultiSelect

Starting with the 2026 Q3 release, the default value of the MultiSelect SummarizeAfter configuration is 10. When users select more than 10 items, the first 10 tags are displayed and the remaining selections are summarized in an overflow tag.

To retain the previous behavior and render every selected item as an individual tag, set SummarizeAfter to null.

Razor
@(Html.Kendo().MultiSelect()
    .Name("multiselect")
    .SummarizeAfter(null)
)
Razor
<kendo-multiselect name="multiselect" summarize-after="@((double?)null)"></kendo-multiselect>

Document Processing and Spreadsheet Package Changes

The following package versions apply:

Package	Version	Notes
Telerik.Spreadsheet.Web	`1.2.0`	Spreadsheet server-side processing package
Telerik.Pdf.Web	`1.2.0`	Required for Telerik UI for ASP.NET Core PDFViewer and Telerik UI for ASP.NET MVC PDFViewer when using Document Processing-based PDF support
Telerik.Export.Core	`1.2.0`	Enables exporting `IEnumerable` data sources to Excel, CSV, PDF, DOCX, RTF, and TXT

Spreadsheet Assembly Renamed

The Spreadsheet dependency assembly has been renamed from Telerik.Web.Spreadsheet to Telerik.Spreadsheet.Web.

PDF Processing Package Renamed

The PDF processing dependency package has been renamed from Telerik.Web.PDF to Telerik.Pdf.Web.

Server-Side Export Package Renamed

The server-side export dependency package has been renamed from Telerik.Core.Export to Telerik.Export.Core.

Migration

Update project references from Telerik.Web.Spreadsheet to Telerik.Spreadsheet.Web.
Add the Telerik.Spreadsheet.Web package explicitly to projects that use Spreadsheet server-side import, export, or processing features.
Replace Telerik.Web.PDF with Telerik.Pdf.Web in applications that use PDFViewer Document Processing integration.
Replace Telerik.Core.Export with Telerik.Export.Core in applications that use server-side export helpers.

Applications that still reference the old assembly or package names must update their project references to restore Spreadsheet, PDF processing, or export functionality.

Accessibility Package Adoption Rendering Changes

Starting with the 2026 Q3 release, several components adopt the new accessibility package. As a result, their rendered HTML structure and CSS class hooks change to align with the updated accessibility implementation.

If your application uses custom CSS, DOM queries, snapshot tests, or automation that target the previous markup, review the following changes and update those integrations accordingly. The Telerik UI for ASP.NET Core wrappers render the underlying Kendo UI for jQuery components, so these markup changes apply to wrapper scenarios as well.

Removed CSS Classes

The following CSS classes are removed as part of the accessibility package adoption:

Component	Removed classes	Notes
Avatar	`k-widget`	Removed from the Avatar wrapper.
ActionSheet	`k-popup`, `k-text-center`, `k-hbox`	`k-popup` is removed from the ActionSheet root element. `k-text-center` and `k-hbox` are removed from the titlebar markup.
FileManager	`k-widget`	Removed from the FileManager wrapper.
MediaPlayer	`k-widget`	Removed from the MediaPlayer wrapper.
TabStrip	`k-rounded-none`	Removed from the TabStrip scroll buttons.
TreeMap	`k-widget`	Removed from the TreeMap wrapper.

Shared Adaptive ActionSheet Titlebar Changes

The ActionSheet titlebar changes propagate to all components that use the shared adaptive ActionSheet implementation. In adaptive mode, the k-text-center and k-hbox classes are removed for the following components:

AutoComplete
ColorPicker
ComboBox
DatePicker
DateRangePicker
DateTimePicker
DropDownList
DropDownTree
MultiColumnComboBox
MultiSelect
TimePicker

Other Structural Changes

The following breaking changes also alter the rendered structure:

Component	Structural change
DockManager	A new `<span class="k-item-actions">` wrapper is added around the tab action buttons.
Splitter	Collapse handles and resize handles now render `<div>` elements instead of `<span>` elements.
TabStrip	The close button now adds the `k-remove-tab` class.
ToolBar	A new `k-toolbar-section` class is introduced for grouped sections. The overflow anchor button now adds the `k-rounded-none` class. Separator markup is also updated and overflow separators no longer render `role="separator"`.

These changes are structural and may affect styling overrides or selectors that depend on removed classes, added wrappers, or previous element nesting.

Scheduler - Enhanced Rendering (HTML and CSS)

Starting with the 2026 Q3 release, the Scheduler adopts enhanced rendering that updates the generated HTML and the CSS hooks used for styling. Custom CSS or DOM queries that target the previous markup must be updated.

The toolbar now uses fillMode="flat", has a new element order, and adds a "New Event" primary button. The navigation buttons are restructured—"Today" is a standalone flat button and Prev/Next are a separate ButtonGroup with fillMode="flat".

The view switcher remains a SegmentedControl at full width but collapses to a MenuButton at narrower widths. The toolbar progressively hides elements as available width decreases (responsive levels 0 through 3).

If you have custom CSS targeting the toolbar navigation ButtonGroup with solid fill, update it to target flat-styled buttons.

Event Element Structure Changed

The internal event structure now uses a flex layout with CSS Container Queries (container-type: size). The k-event-actions class has been removed.

Before:

html

<div class="k-event">
  <span class="k-event-actions"><!-- recurrence icon --></span>
  <div>
    <div class="k-event-template k-event-time">8:00 AM</div>
    <div class="k-event-template">Event Title</div>
  </div>
  <span class="k-event-actions"><!-- delete link --></span>
  <span class="k-resize-handle k-resize-n"></span>
  <span class="k-resize-handle k-resize-s"></span>
</div>

After:

html

<div class="k-event" style="container-type: size">
  <div>
    <div class="k-event-template k-event-title">Event Title</div>
    <div class="k-event-template k-event-time">
      <span class="k-event-recurrence-icon"><!-- icon --></span>
      10:00 AM - 10:30 AM
    </div>
  </div>
  <span class="k-event-recurrence-icon"><!-- icon --></span>
  <span class="k-resize-handle k-resize-n"></span>
  <span class="k-resize-handle k-resize-s"></span>
</div>

Key differences:

Title renders before time (order reversed).
k-event-actions replaced by k-event-recurrence-icon and k-event-continuation spans.
Delete action removed from static rendering.
Multi-day events use k-event-continuation spans with directional chevron icons.
Layout uses display: flex; overflow: visible instead of overflow: hidden.

If you have custom CSS or jQuery selectors targeting .k-event-actions, replace them with .k-event-recurrence-icon or .k-event-continuation.

Header Cell Markup Changed

Day and Week view header cells now render two separate elements instead of a single combined text span.

Before:

html

<th class="k-scheduler-cell k-heading-cell">
  <span class="k-link k-nav-day">Mon 6/13</span>
</th>

After:

html

<th class="k-scheduler-cell k-heading-cell">
  <span class="k-scheduler-date-day">Mon</span>
  <span class="k-link k-nav-day">13</span>
</th>

If you have custom CSS targeting .k-nav-day content format, update it to account for the separate .k-scheduler-date-day element.

Edit Dialog Markup Changed

The quick create and quick edit flows now use a Popover (no overlay) instead of a full Dialog. Form labels use icons instead of text. Actions use the k-popover-actions class.

The full edit dialog date/time section has the following changes:

Date and time pickers are now wrapped in .k-scheduler-edit-form-row containers instead of being direct grid children.
The from/to separator text uses a .k-scheduler-datetime-label class.
The grid changes from a 5-column layout to 3 columns (2.5fr 1fr min-content).
All-day toggle uses a Switch component instead of a checkbox.

If you have custom CSS targeting date/time picker layout inside .k-scheduler-datetime-grid, update selectors to account for the new .k-scheduler-edit-form-row wrapper.

Edit Dialog Uses Dialog Instead of Window

The Scheduler edit dialog now uses a Dialog component instead of a Window. The Window configuration method on the Scheduler's Editable settings now accepts Action<DialogBuilder> instead of Action<WindowBuilder>.

Before (2026 Q2 and earlier):

Razor
@(Html.Kendo().Scheduler<TaskViewModel>()
    .Name("scheduler")
    .Editable(e => e.Window(w => w
        .Title("Edit Event")
        .Width(600)
        .Height(400)
        .Draggable()
        .Resizable()
    ))
)
Razor
<kendo-scheduler name="scheduler">
    <editable>
        <editable-window title="Edit Event" width="600" height="400" draggable="true" resizable="true" />
    </editable>
</kendo-scheduler>

After (2026 Q3 and later):

Razor
@(Html.Kendo().Scheduler<TaskViewModel>()
    .Name("scheduler")
    .Editable(e => e.Window(w => w
        .Title("Edit Event")
        .Width("600px")
        .Modal(m => m.Enabled(true))
    ))
)
Razor
<kendo-scheduler name="scheduler">
    <editable>
        <editable-window title="Edit Event" width="600px">
            <modal enabled="true" />
        </editable-window>
    </editable>
</kendo-scheduler>

The Window method name and <editable-window> tag name are preserved for backward compatibility, but the configurator now exposes DialogBuilder options instead of WindowBuilder options.

New DialogBuilder options available:

Actions – configures the dialog action buttons
ButtonLayout – sets the layout of the action buttons (Normal, Stretched)
Closable – whether the dialog shows a close button
Modal – configures the modal overlay settings
Size – sets the dialog size (Small, Medium, Large)
Content – sets the dialog content
Visible – controls initial visibility
Messages – configures the dialog messages

Previous WindowBuilder options no longer available:

Draggable – the dialog is not draggable
Resizable – the dialog is not resizable
Pinned – no pinned mode
AppendTo – no custom append target
LoadContentFrom – no remote content loading
Position – no custom positioning
Actions (window-style) – the title bar action buttons (Minimize, Maximize, Close) are replaced by dialog action buttons

The month-view overflow indicator now renders a Popover instead of the legacy tooltip. All tooltip-specific class names have been renamed:

Before	After
`.k-tooltip.k-scheduler-tooltip`	`.k-popover.k-scheduler-popover`
`.k-tooltip-title`	`.k-popover-header`
`.k-tooltip-events-container` / `.k-tooltip-events`	`.k-popover-events`
`.k-tooltip-event`	`.k-popover-event`

If you have custom CSS targeting .k-scheduler-tooltip or its child classes, update them to the corresponding .k-scheduler-popover equivalents.

Telerik UI for ASP.NET Core 2026 Q2

New Meridian Theme - Default Theme Moved to Maintenance

Starting with the 2026 Q2 release, a new theme called Meridian is introduced as the recommended default theme for all Telerik UI for ASP.NET Core products. The previous Default theme is moved to maintenance mode.

The Meridian theme is now the default theme used across all demos, documentation, and templates.
The Default theme will continue to be available but will receive only critical bug fixes. No new features or visual updates will be added.
Customers can migrate to the Meridian theme on their own schedule.
This constitutes a major version bump for Kendo Themes due to visual breaking changes.

Kendo UI Icons Package Version

The 2026 Q2 release ships with Kendo UI Icons version 4.9.2 in the source package and wrappers. However, there is also Icons version 5.0.0 available, which includes new icons and updates aligned with the Meridian theme. Icons v5.0.0 is currently in preview mode in the demos and will be officially included in the source packages in an upcoming release.

If you are referencing icons from the Kendo CDN or npm and want to stay aligned with the demos, you can use version 5.0.0. If you prefer to stay aligned with the distributed source, continue using version 4.9.2 until the next official update.

Dialog and Window - ThemeColor Option Removed

The ThemeColor configuration option has been entirely removed from the Dialog and Window components. The ThemeColor property and its associated DialogThemeColor / WindowThemeColor types are no longer available.

Before (2026 Q1 and earlier):

Razor
@(Html.Kendo().Dialog()
    .Name("dialog")
    .ThemeColor("primary")
)

@(Html.Kendo().Window()
    .Name("window")
    .ThemeColor("dark")
)
Razor
<kendo-dialog name="dialog" theme-color="primary"></kendo-dialog>
<kendo-window name="window" theme-color="dark"></kendo-window>

After (2026 Q2 and later):

Razor
@(Html.Kendo().Dialog()
    .Name("dialog")
)

@(Html.Kendo().Window()
    .Name("window")
)
Razor
<kendo-dialog name="dialog"></kendo-dialog>
<kendo-window name="window"></kendo-window>

Light and Dark Theme Colors Removed Globally

The Light and Dark values have been removed from the ThemeColor option across all components that previously supported them. This is a breaking change for consumers explicitly setting ThemeColor to Light or Dark.

Updated ThemeColor Value Sets Per Component

Component	New Allowed ThemeColor Values
Button	`Base`, `Primary`, `Secondary`, `Tertiary`, `Info`, `Success`, `Warning`, `Error`, `Inverse`
FloatingActionButton	`Base`, `Primary`, `Secondary`, `Tertiary`
Icon / SVGIcon	`Inherit`, `Primary`, `Secondary`, `Tertiary`, `Info`, `Success`, `Warning`, `Error`, `Inverse`
Badge	`Base`, `Primary`, `Secondary`, `Tertiary`, `Info`, `Success`, `Warning`, `Error`
Loader	`Base`, `Primary`, `Secondary`, `Tertiary`
Avatar	`Base`, `Primary`, `Secondary`, `Tertiary`
AppBar	`Base`, `Primary`, `Secondary`, `Tertiary`, `Inverse`
BottomNavigation	`Base`, `Primary`, `Secondary`, `Tertiary`, `Inverse`

Migration: Replace any usage of ThemeColor.Light or ThemeColor.Dark with the closest available value (for example, ThemeColor.Base or ThemeColor.Inverse).

Enum Type Changes

The following enum type changes have been made in the Telerik UI for ASP.NET Core wrappers. Components that previously used the generic ThemeColor enum now use component-specific enums with restricted value sets (removing Light and Dark). Similarly, the Button Size property now uses a dedicated ButtonSize enum.

Component	Property	Previous Enum Type	New Enum Type	New Allowed Values
Avatar	ThemeColor	`ThemeColor`	`AvatarThemeColor`	`Base`, `Primary`, `Secondary`, `Tertiary`
Button	Size	`ComponentSize`	`ButtonSize`	`XSmall`, `Small`, `Medium`, `Large`
FloatingActionButton	ThemeColor	`ThemeColor`	`FloatingActionButtonThemeColor`	`Base`, `Primary`, `Secondary`, `Tertiary`
AppBar	ThemeColor	`ThemeColor`	`AppBarThemeColor`	`Base`, `Primary`, `Secondary`, `Tertiary`, `Inverse`
BottomNavigation	ThemeColor	`ThemeColor`	`BottomNavigationThemeColor`	`Base`, `Primary`, `Secondary`, `Tertiary`, `Inverse`

Migration

Before (2026 Q1 and earlier):

csharp

@(Html.Kendo().Avatar()
    .Name("avatar")
    .ThemeColor(ThemeColor.Primary)
)

@(Html.Kendo().Button()
    .Name("btn")
    .Size(ComponentSize.Small)
)

After (2026 Q2 and later):

csharp

@(Html.Kendo().Avatar()
    .Name("avatar")
    .ThemeColor(AvatarThemeColor.Primary)
)

@(Html.Kendo().Button()
    .Name("btn")
    .Size(ButtonSize.Small)
)

New XS (Extra Small) Button Size

The Button component now supports an extra small size (XSmall). This size is intended for use in complex, multi-layered components such as close buttons in component headers.

Razor
@(Html.Kendo().Button()
    .Name("btn")
    .Content("Close")
    .Size(ButtonSize.XSmall)
)
Razor
<kendo-button name="btn" size="ButtonSize.XSmall">Close</kendo-button>

Caret Icons Replaced with Chevron Icons

The caret-alt-down, caret-alt-up, caret-alt-left, and caret-alt-right icons have been replaced with chevron-down, chevron-up, chevron-left, and chevron-right respectively across all components. This includes the SplitButton default arrow icon.

If you have custom CSS or JavaScript targeting the old caret-alt-* icon class names, update them to the corresponding chevron-* names.

Scheduler and Gantt - View Selector Markup Changed

The toolbar view selector in the Scheduler and Gantt components is now rendered with a SegmentedControl instead of a ButtonGroup. Custom CSS or DOM queries that targeted the previous ButtonGroup markup must be updated.

The DateTimePicker also now uses a SegmentedControl for its date/time toggle.

LoaderContainer - Overlay Class Changed

The LoaderContainer now uses the standard k-overlay CSS class instead of the deprecated k-overlay-light variant. The k-overlay-{overlayColor} classes have been removed.

If you have custom CSS targeting k-overlay-light on the LoaderContainer, update it to target k-overlay.

PDFViewer - Loader Overlay Class Changed

The PDFViewer loader overlay now uses the standard k-overlay CSS class instead of k-overlay-light. Custom CSS targeting k-overlay-light on the PDFViewer loader will no longer apply.

Icon Component - New FillMode Property

The Icon and SVGIcon components now support a FillMode property with the following values: Solid, Outline, Duotone.

Telerik UI for ASP.NET Core 2026 Q1

Chat Suggestions Configuration Changes

Starting with the 2026 Q1 release, the Chat component has renamed the scrollable configuration options for suggested actions and suggestions to use a more descriptive layout mode approach.

Renamed Options

Previous Option	New Option
`SuggestedActionsScrollable`	`SuggestedActionsLayoutMode`
`SuggestionsScrollable`	`SuggestionsLayoutMode`

Value Changes

The boolean values have been replaced with the SuggestionsLayoutMode enum:

Previous Value	New Value
`False/True`	`"Wrap/Scroll/ScrollButtons"`

Migration Examples

Before (2025 and earlier):

Razor
    @(Html.Kendo().Chat()
        .Name("chat")
        .SuggestedActionsScrollable(false)
        .SuggestionsScrollable(true)
    )
Razor
    @addTagHelper *, Kendo.Mvc

    <kendo-chat name="chat"
        suggested-actions-scrollable="false"
        suggestions-scrollable="true">
    </kendo-chat>

After (2026 Q1 and later):

Razor
    @(Html.Kendo().Chat()
        .Name("chat")
        .SuggestedActionsLayoutMode(SuggestionsLayoutMode.Wrap)
        .SuggestionsLayoutMode(SuggestionsLayoutMode.Scroll)
    )
Razor
    @addTagHelper *, Kendo.Mvc

    <kendo-chat name="chat"
        suggested-actions-layout-mode="SuggestionsLayoutMode.Wrap"
        suggestions-layout-mode="SuggestionsLayoutMode.Scroll">
    </kendo-chat>

Available Layout Modes

Value	Description
`"Wrap"`	Suggestions wrap to multiple lines within the available space
`"Scroll"`	Suggestions are displayed in a horizontally scrollable container
`"ScrollButtons"`	Suggestions are displayed in a horizontally scrollable container with scroll buttons on each side

TreeView Enhanced Rendering (HTML and CSS)

Starting with the 2026 Q1 release, the TreeView adopts enhanced rendering that updates the generated HTML and the CSS hooks used for styling.

Key HTML Structure Changes

Wrapper class renamed

Before: Position-based wrapper classes were used:

k-treeview-top
k-treeview-mid
k-treeview-bot

After: A single unified wrapper class is used:

k-treeview-item-content

If you have custom CSS or jQuery selectors, replace selectors that target the positional classes with .k-treeview-item-content.

CSS variable for indentation level

Each .k-treeview-item now renders a --kendo-treeview-level CSS custom property that the theme uses to calculate indentation via padding-inline-start.

Example:

html

<li class="k-treeview-item" style="--kendo-treeview-level: 1;">...</li>
<li class="k-treeview-item" style="--kendo-treeview-level: 2;">...</li>

State classes moved

Before: State classes (k-hover, k-focus, k-selected, k-disabled) were applied to the .k-treeview-leaf element.

After: State classes are applied to the .k-treeview-item-content wrapper.

Update any custom selectors accordingly, for example:

css

/* Before */
.k-treeview .k-treeview-leaf.k-selected {
    /* ... */
}

/* After */
.k-treeview .k-treeview-item-content.k-selected {
    /* ... */
}

TabStrip Rendering Changes (HTML and CSS)

Starting with the 2026 Q1 release, the TabStrip no longer renders the k-item class on tab items. Tab elements now use k-tabstrip-item as the primary class.

Key HTML Structure Changes

Tab item class removed

Before: Tab items rendered both classes:

k-item
k-tabstrip-item

After: Tab items render only:

k-tabstrip-item

If you have custom CSS or jQuery selectors targeting .k-item inside TabStrip, replace them with .k-tabstrip-item.

Example:

html

<!-- Before -->
<li class="k-item k-tabstrip-item k-active">Tab 1</li>

<!-- After -->
<li class="k-tabstrip-item k-active">Tab 1</li>

State selectors update

Before: State selectors often targeted .k-item.

After: State selectors should target .k-tabstrip-item.

Update any custom selectors accordingly, for example:

css

/* Before */
.k-tabstrip .k-item.k-active {
    /* ... */
}

/* After */
.k-tabstrip .k-tabstrip-item.k-active {
    /* ... */
}

Sortable integration selectors

If you use Sortable to reorder TabStrip tabs, update the Sortable filter selector from li.k-item to li.k-tabstrip-item.

// Before
filter: "li.k-item"

// After
filter: "li.k-tabstrip-item"

Appearance Defaults Removed

Starting with the 2026 Q1 release, Telerik UI for ASP.NET Core components no longer render default appearance CSS classes. Previously, components automatically added size, rounded, fillMode, and themeColor classes to their HTML output. Instead, these properties now default to null, allowing the theme's CSS to control the component styling.

What Changed

Previously, components had hardcoded defaults like:

Size = ComponentSize.Medium
Rounded = Rounded.Medium
FillMode = ButtonFillMode.Solid
ThemeColor = ThemeColor.Base

Now, these properties default to null. When null, no CSS modifier classes (like k-button-md, k-rounded-md, k-button-solid) are added to the component markup. The theme's base CSS selectors control the default appearance.

Components previously rendered with explicit styling classes like:

html

<!-- Before -->
<button class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-base">Click Me</button>

Now render with minimal base classes:

html

<!-- After -->
<button class="k-button">Click Me</button>

The visual appearance remains the same because Kendo Themes v13+ apply default styles to base classes.

API Changes

None enum value removed from appearance enums
Builder methods now accept nullable types for appearance properties

Removed Enum Values

The following None values have been removed from appearance enums:

Enum	Removed Value
`ComponentSize`	`None`
`FillMode`	`None`
`ButtonFillMode`	`None`
`ChipFillMode`	`None`

Migration for None Value Usage

csharp

// Before - using None to disable styling (NO LONGER VALID)
@(Html.Kendo().Button()
    .Name("btn")
    .Size(ComponentSize.None)  // Compile error!
)

// After - omit the call entirely
@(Html.Kendo().Button()
    .Name("btn")
)

Removed CSS Classes by Category

Size Classes (No Longer Rendered by Default)

Class	Component Types
`k-button-sm`	Buttons
`k-button-md`	Buttons
`k-button-lg`	Buttons
`k-input-sm`	Input components
`k-input-md`	Input components
`k-input-lg`	Input components
`k-picker-sm`	Picker components
`k-picker-md`	Picker components
`k-picker-lg`	Picker components
`k-checkbox-sm`	CheckBox, TreeView
`k-checkbox-md`	CheckBox, TreeView
`k-checkbox-lg`	CheckBox
`k-chip-sm`	Chip, ChipList
`k-chip-md`	Chip, ChipList
`k-chip-lg`	Chip
`k-badge-sm`	Badge
`k-badge-md`	Badge
`k-badge-lg`	Badge
`k-avatar-sm`	Avatar
`k-avatar-md`	Avatar
`k-avatar-lg`	Avatar
`k-loader-sm`	Loader
`k-loader-md`	Loader
`k-loader-lg`	Loader

Rounded Classes (No Longer Rendered by Default)

Class	Description
`k-rounded-sm`	Small border radius
`k-rounded-md`	Medium border radius
`k-rounded-lg`	Large border radius
`k-rounded-full`	Full/pill border radius

FillMode Classes (No Longer Rendered by Default)

Class	Component Types
`k-button-solid`	Buttons
`k-button-solid-base`	Buttons with base theme color
`k-button-solid-primary`	Buttons with primary theme color
`k-button-flat`	Flat buttons
`k-button-flat-base`	Flat buttons with base theme color
`k-button-flat-primary`	Flat buttons with primary theme color
`k-button-outline`	Outline buttons
`k-input-solid`	Input components
`k-input-flat`	Input components
`k-input-outline`	Input components
`k-picker-solid`	Picker components
`k-picker-flat`	Picker components
`k-picker-outline`	Picker components
`k-chip-solid`	Chip
`k-chip-solid-base`	Chip with base theme color
`k-chip-outline`	Chip
`k-badge-solid`	Badge
`k-badge-outline`	Badge
`k-avatar-solid`	Avatar
`k-avatar-outline`	Avatar

ThemeColor Classes (No Longer Rendered by Default)

Class Pattern	Examples
`k-button-solid-{color}`	`k-button-solid-base`, `k-button-solid-primary`, `k-button-solid-secondary`
`k-button-flat-{color}`	`k-button-flat-base`, `k-button-flat-primary`
`k-chip-solid-{color}`	`k-chip-solid-base`, `k-chip-solid-primary`
`k-badge-solid-{color}`	`k-badge-solid-primary`, `k-badge-solid-secondary`

Default Appearance Changes - Affected Components

The following components no longer render default appearance classes:

Input Components

Component	fillMode	size	rounded	themeColor
AutoComplete	Removed	Removed	Removed	-
ComboBox	Removed	Removed	Removed	-
DateInput	Removed	Removed	Removed	-
DatePicker	Removed	Removed	Removed	-
DateRangePicker	Removed	Removed	Removed	-
DateTimePicker	Removed	Removed	Removed	-
DropDownList	Removed	Removed	Removed	-
DropDownTree	Removed	Removed	Removed	-
MaskedTextBox	Removed	Removed	Removed	-
MultiSelect	Removed	Removed	Removed	-
NumericTextBox	Removed	Removed	Removed	-
OTPInput	Removed	Removed	Removed	-
TextArea	Removed	Removed	Removed	-
TextBox	Removed	Removed	Removed	-
TimeDurationPicker	Removed	Removed	Removed	-
TimePicker	Removed	Removed	Removed	-
ColorPicker	Removed	Removed	Removed	-
ColorGradient	-	Removed	-	-
ColorPalette	-	Removed	-	-
Signature	Removed	Removed	Removed	-

Button Components

Component	fillMode	size	rounded	themeColor
Button	Removed	Removed	Removed	Removed
ButtonGroup	Removed	-	-	-
SplitButton	Removed	Removed	Removed	Removed
DropDownButton	Removed	Removed	Removed	Removed
FloatingActionButton	Removed	Removed	Removed	Removed

The ButtonGroup's Items.Badge.ThemeColor no longer render default appearance classes as well. It defaults to undefined which enforces the theme to control the default color

Chip Components

Component	fillMode	size	rounded	themeColor
Chip	Removed	Removed	Removed	Removed
ChipList	-	Removed	-	-

Indicator Components

Component	fillMode	size	rounded	themeColor
Avatar	Removed	Removed	Removed	Removed
Badge	Removed	Removed	Removed	Removed
Loader	-	Removed	-	Removed

The default themeColor of the Badge component is now primary.

Component	fillMode	size	rounded	themeColor
BottomNavigation	Removed	-	-	Removed
Breadcrumb	-	Removed	-	-
TabStrip	-	Removed	-	-

Selection Components

Component	fillMode	size	rounded	themeColor
CheckBox	-	Removed	Removed	-
RadioButton	-	Removed	-	-
Switch	-	Removed	Removed	-

Data Components

Component	fillMode	size	rounded	themeColor
Grid	-	Removed	-	-
ListBox	-	Removed	-	-
Pager	-	Removed	-	-
TreeView	-	Removed	-	-

Layout & Containers

Component	fillMode	size	rounded	themeColor
AppBar	-	-	-	Removed
Dialog	-	-	-	Removed
Window	-	-	-	Removed
ToolBar	Removed	Removed	-	-
Form	-	Removed	-	-

Notification

Starting with 2026 Q1 version when no type parameter is passed the the show() method, the Notification will be displayed with default colors. Previously, the default value of the type property was info. If you need to acheive the previous behavior you can use the approaches demonstrated below:

Razor

var notification = $("#notification").data("kendoNotification");

notification.show("Some text", "info");

//or

notification.info("Some text");

Icons

Component	fillMode	size	rounded	themeColor
Icon	-	Removed	-	Removed
SVGIcon	-	Removed	-	Removed

Migration Guide

For HTML Helper (MVC)

If you need explicit styling, set the options:

csharp

// Before (implicit defaults)
@(Html.Kendo().Button()
    .Name("myButton")
    .Content("Click Me")
)
// Rendered: <button class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-base">

// After (explicit sizing)
@(Html.Kendo().Button()
    .Name("myButton")
    .Content("Click Me")
    .Size(ComponentSize.Medium)
    .Rounded(Rounded.Medium)
    .FillMode(ButtonFillMode.Solid)
    .ThemeColor(ThemeColor.Base)
)
// Rendered: <button class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-base">

For Tag Helpers (Core)

html

<!-- Before (implicit defaults) -->
<kendo-button name="myButton">Click Me</kendo-button>

<!-- After (explicit sizing) -->
<kendo-button name="myButton" size="ComponentSize.Medium" rounded="Rounded.Medium" fill-mode="ButtonFillMode.Solid" theme-color="ThemeColor.Base"> Click Me </kendo-button>

Grid Component Changes

The Grid's internal elements (toolbar, pager, buttons) also no longer render default classes:

csharp

// Before
@(Html.Kendo().Grid<Product>()
    .Name("grid")
    // Size defaulted to Medium
)

// After - Grid Size is null by default
// Set explicitly if needed:
@(Html.Kendo().Grid<Product>()
    .Name("grid")
    .Size(ComponentSize.Medium)
)

Dialog Actions

csharp

// Before
.Actions(actions =>
{
    actions.Add().Text("OK").FillMode(ButtonFillMode.None); // No longer valid
})

// After
.Actions(actions =>
{
    actions.Add().Text("OK"); // Omit FillMode for default styling
})

Custom CSS Updates

If you have custom CSS targeting size classes:

css

/* Before - targeting medium buttons */
.k-button.k-button-md {
    /* custom styles */
}

/* After - target base class (theme provides defaults) */
.k-button {
    /* custom styles */
}

/* Or explicitly set size in code and target that class */

Theme Version Requirement

This change requires Kendo Themes v13.0.0 or later. Update your theme package references:

xml

<!-- NuGet packages -->
<PackageReference Include="Telerik.UI.for.AspNet.Core" Version="2026.1.xxx" />

Or CDN references:

html

<link rel="stylesheet" href="https://kendo.cdn.telerik.com/themes/13.0.0/default/default-main.css" />

Benefits

Cleaner DOM - Components render fewer CSS classes
Flexible Theming - Easier to customize default appearance via CSS
Smaller Markup - Reduced HTML output size
Centralized Defaults - Styling defaults managed in CSS, not server-side code

Virtual List Rendering Changes

Starting with the 2026 Q1 release, the Virtual List introduces changes to its HTML rendering.

Aspect	Before (2025 and earlier)	After (2026 Q1 and later)
List element class	`k-virtual-content k-list-ul`	`k-list-ul`
Grouped data	All group labels and items in a single `<ul>`	Separate `<ul>` per group, each with its own group label

Before:

html

<ul class="k-virtual-content k-list-ul">
    <li class="k-list-item-group-label">Group A</li>
    <li class="k-list-item">Item 1</li>
    <li class="k-list-item">Item 2</li>
    <li class="k-list-item-group-label">Group B</li>
    <li class="k-list-item">Item 3</li>
</ul>

After:

html

<ul class="k-list-ul">
    <li class="k-list-item-group-label">Group A</li>
    <li class="k-list-item">Item 1</li>
    <li class="k-list-item">Item 2</li>
</ul>
<ul class="k-list-ul">
    <li class="k-list-item-group-label">Group B</li>
    <li class="k-list-item">Item 3</li>
</ul>

If you have custom CSS or jQuery selectors targeting k-virtual-content, update them to use .k-list-ul.

MultiColumnComboBox Sticky Group Header Rendering Changes

Starting with the 2026 Q1 release, the MultiColumnComboBox component introduces a change to how the sticky group header is rendered when the data is grouped.

Aspect	Before (2025 and earlier)	After (2026 Q1 and later)
CSS class	`.k-list-group-sticky-header`	`.k-table-group-sticky-header`
Element	`<tr>` inside `<table>`	`<div>` outside `<table>`

Before:

html

<table class="k-table">
    <tr class="k-list-group-sticky-header">
        <td colspan="...">Group Name</td>
    </tr>
    <!-- table rows -->
</table>

After:

html

<div class="k-table-group-sticky-header">Group Name</div>
<table class="k-table">
    <!-- table rows -->
</table>

If you have custom CSS or jQuery selectors targeting .k-list-group-sticky-header for the MultiColumnComboBox, update them to use .k-table-group-sticky-header:

css

/* Before */
.k-multicolumncombobox .k-list-group-sticky-header { /* ... */ }

/* After */
.k-multicolumncombobox .k-table-group-sticky-header { /* ... */ }

Diagram

For the fluent wrappers DashTypes were a string and are now enums.

HtmlHelpers

DiagramConnectionContentBorderSettingsBuilder
DiagramConnectionDefaultsContentBorderSettingsBuilder
DiagramConnectionDefaultsEndCapStrokeSettingsBuilder
DiagramConnectionDefaultsStartCapStrokeSettingsBuilder
DiagramConnectionEndCapStrokeSettingsBuilder
DiagramConnectionStartCapStrokeSettingsBuilder
DiagramEditableResizeHandlesHoverStrokeSettingsBuilder
DiagramEditableResizeHandlesStrokeSettingsBuilder
DiagramSelectableStrokeSettingsBuilder
DiagramShapeConnectorDefaultsHoverStrokeSettingsBuilder
DiagramShapeConnectorDefaultsStrokeSettingsBuilder
DiagramShapeConnectorHoverStrokeSettingsBuilder
DiagramShapeConnectorStrokeSettingsBuilder
DiagramShapeDefaultsConnectorDefaultsHoverStrokeSettingsBuilder
DiagramShapeDefaultsConnectorDefaultsStrokeSettingsBuilder
DiagramShapeDefaultsConnectorHoverStrokeSettingsBuilder
DiagramShapeDefaultsConnectorStrokeSettingsBuilder
DiagramShapeDefaultsStrokeSettingsBuilder
DiagramShapeStrokeSettingsBuilder

TagHelpers

DiagramConnectionContentBorderSettingsTagHelper
DiagramConnectionDefaultsContentBorderSettingsTagHelper
DiagramConnectionDefaultsEndCapStrokeSettingsTagHelper
DiagramConnectionDefaultsStartCapStrokeSettingsTagHelper
DiagramConnectionEndCapStrokeSettingsTagHelper
DiagramConnectionStartCapStrokeSettingsTagHelper
DiagramEditableResizeHandlesHoverStrokeSettingsTagHelper
DiagramEditableResizeHandlesStrokeSettingsTagHelper
DiagramSelectableStrokeSettingsTagHelper
DiagramShapeConnectorDefaultsHoverStrokeSettingsTagHelper
DiagramShapeConnectorDefaultsStrokeSettingsTagHelper
DiagramShapeConnectorHoverStrokeSettingsTagHelper
DiagramShapeConnectorStrokeSettingsTagHelper
DiagramShapeDefaultsConnectorDefaultsHoverStrokeSettingsTagHelper
DiagramShapeDefaultsConnectorDefaultsStrokeSettingsTagHelper
DiagramShapeDefaultsConnectorHoverStrokeSettingsTagHelper
DiagramShapeDefaultsConnectorStrokeSettingsTagHelper
DiagramShapeDefaultsStrokeSettingsTagHelper
DiagramShapeStrokeSettingsTagHelper