Breaking Changes in 13.0.0

Updated on Feb 11, 2026

Default Apperance Settings

The default values of the following parameters have changed to null:

• FillMode
• Rounded
• Size
• ThemeColor

The following information and code snippets use the Button component as an example, but the same idea applies to all components, which use the above parameters.

Starting from version 13.0.0, the default background, border and dimension styles depend on the main component CSS class rather than explicit default parameter values that render additional CSS classes. Technically, changing the default value of a parameter is a breaking change, but your Blazor apps may not require any modifications:

• Components that do not use appearance parameters maintain their styling.
• Components that use explicit apperance parameters (for example, Primary ThemeColor or Large Size) maintain their styling.
• You may need to adjust CSS selectors in custom CSS rules, if these rules rely on classes that no longer render by default. See Rendering Changes in Version 13.0.0.

The following configurations produce equivalent UI in all versions of Telerik UI for Blazor, except the explicit null settings that are only valid for version 13.0.0 and above.

<TelerikButton>
    Button Text
</TelerikButton>

<TelerikButton FillMode="@ThemeConstants.Button.FillMode.Solid"
               Rounded="@ThemeConstants.Button.Rounded.Medium"
               Size="@ThemeConstants.Button.Size.Medium"
               ThemeColor="@ThemeConstants.Button.ThemeColor.Base">
    Button Text
</TelerikButton>

<TelerikButton FillMode="solid"
               Rounded="md"
               Size="md"
               ThemeColor="base">
    Button Text
</TelerikButton>

<TelerikButton FillMode="@null"
               Rounded="@null"
               Size="@null"
               ThemeColor="@null">
    Button Text
</TelerikButton>