blazor-docs/upgrade/overview.md

---
title: How to Upgrade
page_title: How to Upgrade
description: How to Upgrade the version of the Telerik UI for Blazor package.
slug: upgrade-tutorial
tags: upgrade,tutorial,changes,update
published: True
position: 0
---

# How to Upgrade Telerik UI for Blazor

This article explains how to upgrade to a new version of Telerik UI for Blazor.

To upgrade the Telerik components, you need to update their NuGet package reference, and, if you use them, the CDN links.

The **latest** available version of UI for Blazor is **{{site.uiForBlazorLatestVersion}}**.

>tip Before starting an upgrade of your project, you may find it useful to review the following information:
>
> * [Framework Versions Support]({%slug framework-versions-support%}) - this will let you see what version of the .NET framework you need and which UI for Blazor versions work on it.
> * [UI for Blazor Release History](https://www.telerik.com/support/whats-new/blazor-ui/release-history) — reviewing the release notes for all releases you go through will let you see what has changed, what fixes, features and components have been implemented so you are better prepared to meet your project's challenges.
> * Whether you are affected by a breaking change. The [List of Telerik UI for Blazor Versions with Breaking Changes]({%slug versions-with-breaking-changes%}) article shows which releases of our component suite have breaking changes. Review the information for the releases you go through so you can evaluate whether you will be affected by anything.

In this article:

* [Upgrade Process](#upgrade-process)
* [Upgrade with Upgrade Wizard](#upgrade-wizard)
* [Upgrade from Trial to Commercial](#upgrade-from-trial-to-commercial)
* [Troubleshooting](#troubleshooting)


## Upgrade Process

To upgrade the Telerik UI for Blazor components used in your project, perform the following steps:

1. @[template](/_contentTemplates/common/general-info.md#ensure-nuget-packge-for-upgrade)

1. Update the version of the `Telerik.UI.for.Blazor` NuGet package in all applicable projects. If you are using a trial version, the package name is `Telerik.UI.for.Blazor.Trial`.

1. If you are [loading `telerik-blazor.js` from CDN]({%slug common-features-cdn%}#javascript-urls), update the version number in the CDN URL to match the NuGet package version.

1. If you are [loading themes from CDN]({%slug common-features-cdn%}#css-theme-urls), update the version number in the theme URL. For example, if you are upgrading to Telerik UI for Blazor {{site.uiForBlazorLatestVersion}}, the version number in the theme URL must be:
    * `{{site.themesVersion}}` if using [UNPKG CDN]({%slug common-features-cdn%}#unpkg-cdn)
    * `{{site.uiForBlazorLatestVersion}}` if using the [Telerik CDN]({%slug common-features-cdn%}#telerik-cdn)

1. If you are using a local theme stylesheet in `wwwroot`, then replace it. For example, if the app is using a [custom theme]({%slug themes-customize%}), then recreate it with the [ThemeBuilder](https://docs.telerik.com/themebuilder). Or, if the [project was created with the Telerik® UI for Blazor Visual Studio Extensions]({%slug getting-started-vs-integration-new-project%}), then [download the required built-in theme]({%slug themes-overview%}#built-in-themes) and add it to the project.

1. If the application is localized, [update the Telerik localization resource (`.resx`) files]({%slug globalization-localization%}#step-2-add-resouce-files). Otherwise, you may see [exceptions related to missing localization strings]({%slug common-kb-value-cannot-be-null-parameter-format%}).

1. Clear the browser cache and optionally [add a cache buster for the Telerik CSS and JavaScript files]({%slug common-kb-browser-cache-buster%}).

## Upgrade Wizard

To upgrade the version of Telerik UI for Blazor you can use the [Upgrade Wizard]({%slug getting-started-vs-integration-upgrade-project%}) that comes as part of the [Telerik UI for Blazor Visual Studio Extension]({% slug getting-started-vs-integration-overview %}).

## Upgrade from Trial to Commercial

If you have just purchased a license and you need to migrate from the trial package to the licensed version, perform the following steps:

1. @[template](/_contentTemplates/common/general-info.md#ensure-nuget-packge-for-upgrade)

1. Replace the reference to the `Telerik.UI.for.Blazor.Trial` package in your project with a reference to the `Telerik.UI.for.Blazor` package.

    * If you are referencing other Telerik trial packages that you now have a license for, remove the `.Trial` from their names too.

1. If you are using static assets for our JS Interop file and/or Theme, update their path to match the package name (remove the `.Trial` part):

    **HTML**
    
        <!-- FROM
        <script src="_content/Telerik.UI.for.Blazor.Trial/js/telerik-blazor.js" defer></script>
        
        TO
        -->
        <script src="_content/Telerik.UI.for.Blazor/js/telerik-blazor.js" defer></script>
        
        
        <!-- FROM
        <link rel="stylesheet" href="_content/Telerik.UI.for.Blazor.Trial/css/kendo-theme-default/all.css" />
        
        TO
        -->
        <link rel="stylesheet" href="_content/Telerik.UI.for.Blazor/css/kendo-theme-default/all.css" />
        
        

The Trial version of our assembly has the `Telerik.Blazor Trial version` Title. You can see it by Right clicking the assembly > Properties > File Description. You can find the assembly by extracting the `.nupgk` file like a `.zip` archive, or in the publish location.

## Troubleshooting

## Microsoft.JSInterop.JSException: Could not find ...

The most common problem you will encounter when upgrading is wrong references to our JS Interop file. You can read more about fixing them in the [Troubleshoot JavaScript Errors]({%slug troubleshooting-js-errors%}) article.

## I Still See the Trial Watermark and Banner

While using a trial license, a watermark will be rendered over the components and you will see a banner with the following message:

> Thank you for using the Trial Version of Telerik UI for Blazor to build more powerful applications faster. Purchase the Commercial Version now to get access to all product updates and the Telerik expert support.

If you have a commercial license, but you still see the trial watermark and banner, especially after publishing an app to a staging or live server, your build has used the trial `Telerik.Blazor.dll` assembly.

The most common reason for the problem is that the framework decides to incorrectly copy a trial version of the Telerik UI for Blazor assembly into the `dist` folder of the app, even though it puts the correct licensed version at the root of the publish folder. This seems like a problem in the build process of the framework.

To fix this in the meantime, try the following process (you can try a new test build after each step where you make a change):

1. Ensure that the licensed package is referenced in the project (`Telerik.UI.for.Blazor` instead of `Telerik.UI.for.Blazor.Trial`). Make sure this is also the case on the build machine. Sometimes a failed build or locked files may prevent a file from being updated and so the build machine may be using a trial reference.

1. Uninstall any Trial installations from the build machine, dev PC and live server.

1. If you have created local NuGet feeds, ensure they do not contain Trial versions of our packages.

1. [Clean the NuGet packages](https://docs.microsoft.com/en-us/nuget/consume-packages/managing-the-global-packages-and-cache-folders#clearing-local-folders) on the build machine, dev PC and live server.

1. Clean the projects.

1. Delete the `bin` and `obj` folders where packages and assemblies may be cached.

1. Re-build your project.


## See Also

* [What You Need to Use Telerik UI for Blazor]({%slug getting-started/what-you-need%})
* [Get Started with Client-side Blazor]({%slug getting-started/client-side%})
* [Get Started with Server-side Blazor]({%slug getting-started/server-side%})