2026 Releases

Updated on Aug 12, 2026

This article lists the breaking or important changes in the 2026 releases of Kendo UI. For the complete list of changes in the UI components, see the product release history.

Kendo UI 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.

javascript

$("#multiselect").kendoMultiSelect({
    summarizeAfter: null
});

Document Processing and Spreadsheet Package Changes for ASP.NET Integrations

The following package versions apply to these server-side integration scenarios:

Package	Version	Notes
Telerik.Spreadsheet.Web	1.2.0	Spreadsheet server-side processing package
Telerik.Pdf.Web	1.2.0	Required for ASP.NET Core and ASP.NET MVC PDFViewer integration 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.

If your Kendo UI application relies on these ASP.NET server-side features, update project references accordingly and add the Telerik.Spreadsheet.Web package explicitly. Likewise, replace Telerik.Web.PDF with Telerik.Pdf.Web and Telerik.Core.Export with Telerik.Export.Core where applicable.

This change affects server-side processing and packaging only. It does not change the client-side Kendo UI for jQuery Spreadsheet API.

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.

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.

Toolbar Markup Changed

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.

Month View "More Events" Tooltip Replaced with Popover

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.

Kendo UI 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 Kendo UI 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.

To switch to the Meridian theme, update your stylesheet reference:

html

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

<!-- After -->
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/themes/14.0.0/meridian/meridian-main.css" />

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. Previously available values (primary, dark, light, none) are no longer accepted.

Before (2026 Q1 and earlier):

javascript

$("#dialog").kendoDialog({
    themeColor: "primary"
});

$("#window").kendoWindow({
    themeColor: "dark"
});

After (2026 Q2 and later):

javascript

// themeColor is no longer a valid option
$("#dialog").kendoDialog({});

$("#window").kendoWindow({});

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 using themeColor: "light" or themeColor: "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, "base" or "inverse").

Button Size Option Type Change

The Button size option now accepts the additional value "xsmall" (rendered as k-button-xs). In the ASP.NET wrappers, the Size property enum type has changed from ComponentSize to ButtonSize to accommodate this new value. The ComponentSize enum does not include XSmall, so the new ButtonSize enum is used instead.

New XS (Extra Small) Button Size

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

The following components now use XS-sized buttons internally:

• Dialog - close button
• Window - close, minimize, maximize buttons
• Chat - attachment actions, pinned toolbar close button, message actions, quick reply remove button, failed message retry button
• Upload - remove and retry buttons
• TabStrip - close button
• Timeline - card expand/collapse button
• Spreadsheet - sheet bar buttons

javascript

$("#button").kendoButton({
    size: "xsmall"
});

Caret Icons Replaced with Chevron Icons

The caret-alt-down, caret-alt-up, caret-alt-left, and caret-alt-right icons (and their SVG counterparts caretAltDownIcon, caretAltUpIcon, etc.) have been replaced with chevron-down, chevron-up, chevron-left, and chevron-right respectively across all components.

Similarly, caret-double-alt-left and caret-double-alt-right are replaced with their chevron-double equivalents.

Note: caret-alt-to-*, caret-alt-expand, and sort indicator icons (caretBl*, caretTr*) remain unchanged.

Affected Components

Component	Changed Icon(s)
SplitButton	Default arrowButtonIcon changed from caret-alt-down to chevron-down
SplitButton (Toolbar)	Default arrowButtonSvgIcon changed from caretAltDownIcon to chevronDownIcon
DropDownList, ComboBox, MultiColumnComboBox, DropDownTree	Dropdown arrow icon
DateInput, DateTimePicker, TimePicker	Navigation icons
NumericTextBox, Slider, ColorPicker	Spinner/navigation icons
Grid (group headers), TreeList	Expand/collapse icons
Scheduler, Gantt	Toolbar navigation icons
TabStrip, Splitter	Scroll/navigation icons
ListBox, Menu, Pager	Navigation icons
Spreadsheet, Toolbar	Various action icons

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.

Tooltip - New themeColor Option

The Tooltip component now supports a themeColor option. Available values are: base, inverse, info, success, warning, error.

javascript

$("#tooltip").kendoTooltip({
    themeColor: "info"
});

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. The property applies a k-{fillMode} CSS class to the icon element.

Kendo UI 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):

javascript

$("#chat").kendoChat({
    suggestedActionsScrollable: false,
    suggestionsScrollable: true
});

After (2026 Q1 and later):

javascript

$("#chat").kendoChat({
    suggestedActionsLayoutMode: "wrap",
    suggestionsLayoutMode: "scroll"
});

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 { /* ... */ }

Component Appearance Defaults Removed

Starting with the R1 2026 release, Kendo UI for jQuery components no longer render default appearance CSS classes. Previously, components automatically added size, rounded, fillMode, and themeColor classes to their DOM elements. Instead, these properties default to undefined, allowing the theme's CSS to control the component styling.

What Changed

Previously, components had hardcoded defaults like:

• size: "medium"
• rounded: "medium"
• fillMode: "solid"
• themeColor: "base"

Now, these properties default to undefined. When undefined, 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.

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
k-calendar-md	Calendar, MultiViewCalendar
k-table-md	Grid, TreeList, PivotGrid, and other table-based components
k-toolbar-md	Toolbar
k-form-md	Form

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)

The combined fillMode-themeColor class pattern has been split into separate classes:

Versions prior to 2026.1	Versions 2026.1 and later
k-button-solid-base	k-button-solid
k-button-solid-primary	k-button-solid k-button-primary
k-button-solid-secondary	k-button-solid k-button-secondary
k-button-flat-base	k-button-flat
k-button-flat-primary	k-button-flat k-button-primary
k-chip-solid-base	k-chip-solid
k-chip-solid-primary	k-chip-solid k-button-primary

Default fillMode classes (k-button-solid, k-input-solid, etc.) are no longer rendered when using theme defaults:

Class	Component Types
k-button-solid	Buttons (removed when default)
k-button-flat	Flat buttons (rendered only when explicitly set)
k-button-outline	Outline buttons (rendered only when explicitly set)
k-input-solid	Input components (removed when default)
k-input-flat	Input components (rendered only when explicitly set)
k-input-outline	Input components (rendered only when explicitly set)
k-picker-solid	Picker components (removed when default)
k-picker-flat	Picker components (rendered only when explicitly set)
k-picker-outline	Picker components (rendered only when explicitly set)
k-chip-solid	Chip (removed when default)
k-chip-outline	Chip (rendered only when explicitly set)
k-badge-solid	Badge (removed when default)
k-badge-outline	Badge (rendered only when explicitly set)
k-avatar-solid	Avatar (removed when default)
k-avatar-outline	Avatar (rendered only when explicitly set)

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	-
DropDownGrid	Removed	Removed	Removed	-
DropDownList	Removed	Removed	Removed	-
DropDownTree	Removed	Removed	Removed	-
MaskedTextBox	Removed	Removed	Removed	-
MultiSelect	Removed	Removed	Removed	-
MultiSelectTree	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
MenuButton	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

Starting with the 2026 Q1 release, the Badge component renders with the primary appearance by default. Because appearance defaults are now theme-controlled, the themeColor option will be undefined when not set, but the theme applies the primary styling. To preserve the previous (secondary) look, explicitly set themeColor: 'secondary'.

Navigation Components

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:

js

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

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

//or

notification.info("Some text");

Icons

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

Components with Internal Template Changes

The following components have internal buttons, inputs, checkboxes, or other elements that previously had hardcoded default appearance classes. These classes have been removed:

• Calendar, MultiViewCalendar
• ColumnMenu
• Dialog
• Editor
• FileBrowser
• FileManager
• Filter, FilterMenu
• Gantt
• Grid, TreeList, PivotGrid
• Map
• MediaPlayer
• Menu
• Pager
• PanelBar
• PDFViewer
• Scheduler
• Spreadsheet
• TabStrip
• TaskBoard
• Timeline
• TreeView
• Upload

Migration Guide

If You Need Explicit Styling

If your application relies on the previous default classes, you can explicitly set the options:

javascript

// Before (implicit defaults)
$("#button").kendoButton();
// Rendered: <button class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-base">

// After (explicit sizing)
$("#button").kendoButton({
    size: "medium",
    rounded: "medium",
    fillMode: "solid",
    themeColor: "base"
});
// Rendered: <button class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-base">

If You Have Custom CSS Targeting Size Classes

Update your CSS selectors to target base classes or use explicit options:

css

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

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

/* Or set explicit size and target that */
.k-button.k-button-md {
    /* only applies when size: "medium" is explicitly set */
}

If You Use the "none" Value

The "none" value has been removed from size, fillMode, and rounded options. If you were using "none" to disable styling:

javascript

// Before
$("#button").kendoButton({ size: "none" }); // No longer supported

// After - omit the option entirely
$("#button").kendoButton();

Learn how to restore previous default appearance values for Kendo UI for jQuery components in the article linked here.

Theme Version Update

The Kendo themes have been updated to version 13.0.0 (from 12.x). The new theme version provides default styling via CSS instead of requiring JavaScript to add explicit modifier classes.

Benefits

1. Cleaner DOM - Components render fewer CSS classes
2. Flexible Theming - Easier to customize default appearance via CSS
3. Smaller Markup - Reduced HTML output size
4. Centralized Defaults - Styling defaults managed in CSS, not JavaScript

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 { /* ... */ }