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Telerik NuGet Feed Troubleshooting

This article summarizes the issues that may occur when you work with the Telerik UI for Blazor library and the online Telerik NuGet feed, and their solutions.

Regardless of the cause for the issue, it is recommended that you start from the section on the commonly occurring issues.

Tips for Handling Common NuGet Issues

The most common reasons for issues with the private Telerik NuGet feed are related to:

  • Authentication and credentials.
  • Licensing. For example, requesting commercial packages with a trial license or vice-versa.
  • Missing or wrong local configuration (NuGet.Config).
  • Network connectivity issues, including proxies and firewalls.

Errors like Unable to load the service index for source don't indicate the exact cause of the problem. In such cases, check the additional error information which usually provides an error code.

To verify if you can access the Telerik NuGet server and the expected packages, open the URL directly in the web browser and enter your Telerik credentials in the prompt.

As a result, you will see a JSON output with the NuGet packages and versions that are available for you. Depending on your license, search for Telerik.UI.for.Blazor or Telerik.UI.for.Blazor.Trial.

If the above URL doesn't open, you have either come across a local networking issue or the NuGet server is down.

If you can access the feed in the browser, but you do not see the packages in Visual Studio, most likely the problem is caused by entering wrong credentials or using a different Telerik account. Make sure your saved credentials are correct. Also, you must not have a NuGet.Config file in your project as it may bring in invalid credentials and project-level configuration files override the global ones.

Removing Saved Credentials

If you suspect that your saved credentials are wrong, use the following steps to remove them from Windows and, then, add the correct ones:

  1. Remove the saved credentials in the Windows Credential Manager. These credentials will appear as or entries.
  2. Remove the Telerik NuGet package source from Visual Studio.
  3. If you have added the Telerik package source by NuGet CLI, try to remove it from the CLI by running the following commands:
  4. Check if you have any credentials stored in %AppData%\NuGet\Nuget.Config. If so, remove them.
  5. Try to reset the Visual Studio user data by forcing NuGet to ask for authentication.
  6. Restart Visual Studio.
  7. Enter the Telerik NuGet package source again through Visual Studio or CLI. If you are using the feed in a .NET Core application, store your credentials as plain text.

Error 401 Unauthorized

If your credentials are correct and your license includes the requested product and version, then the password probably contains special characters. You need to escape these characters or the authentication can fail on the NuGet server. For example, a common character you must escape is the ampersand (&); however, the character causing the issue may be as unique as the section character (§).

To solve the issue:

  1. Change the password so that it doesn't include characters you need to escape.
  2. Escape the special characters before storing the credentials. For example, my§uper&P@§§word encodes to my§uper&P@§§word.

Avoid using an online encoder utility for a password. Instead, use a Powershell command:

Add-Type -AssemblyName System.Web

Powershell Encoding

Unable to Find Package

If the error occurs for the Telerik.UI.for.Blazor package, the Telerik NuGet source may not be added or enabled. The possible causes are:

If the error occurs for the Telerik.FontIcons and Telerik.SvgIcons icon packages, the NuGet client is not using as a NuGet source. The possible causes are:

  • The source is disabled.
  • There is packageSourceMapping, which forces the NuGet client to search for the icon packages in the source. However, the icon packages are published on

Error 503 Service Unavailable

If you get a message like Unable to load the service index for source and error 503 (Service unavailable), check the Telerik NuGet server health at the Telerik live services status page.

In urgent cases, download the NuGet packages from your Telerik Account Downloads page. Then, set up a local NuGet feed.

Package Version Not Found

You may encounter an error similar to ProjectName depends on Telerik.UI.for.Blazor (>= 3.6.1) but Telerik.UI.for.Blazor 3.6.1 was not found. An approximate best match of Telerik.UI.for.Blazor 3.7.0 was resolved.

This error means that version 3.6.1 is outside the subscription period of your license.

To solve the issue, use a different version or ask the license holder at your company to assign you another license that includes the desired product version.

Unable to Resolve Package due to PackageSourceMapping

Incorrect package source mapping can result in errors similar to:

NU1100 Unable to resolve 'Telerik... (>= ...)' for 'net...'. PackageSourceMapping is enabled, the following source(s) were not considered: ...

The solution is to check the Package Source Mapping settings in Visual Studio, or review all applicable NuGet.Config files on the machine. Then, adjust the package source mapping configuration.

See Also

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