Unable to Connect to Telerik_v3 Package Source When Behind a WebProxy

Updated on Oct 6, 2026

Environment

Product	UI for ASP.NET AJAX
Version	2026.3.811

Description

I cannot connect to the Telerik_v3 package source behind a WebProxy. A login popup appears, but I do not have credentials for the WebProxy. My project cannot use Telerik.UI.for.AspNet.AJAX version 2026.3.812. I want to include this package in my project without relying on the online package source.

Cause

The issue occurs because the WebProxy blocks access to the Telerik online feed, making it impossible to download the NuGet package directly. This prevents the project from using the required package.

Solution

To resolve this issue, download the required NuGet package from your Telerik account and install it from a local package source. Follow these steps:

1. Download the Telerik.UI.for.AspNet.AJAX.2026.3.812.nupkg package from your Telerik account.
2. Create a local folder, for example, C:\TelerikPackages.
3. Place the downloaded NuGet package in the C:\TelerikPackages folder.
4. Open Visual Studio and go to Tools > NuGet Package Manager > Package Manager Settings > Package Sources.
5. Add C:\TelerikPackages as a new package source.
6. In the NuGet Package Manager, select the new local source and install Telerik.UI.for.AspNet.AJAX version 2026.3.812.

Important Notes:

• Keep nuget.org enabled in the package sources list. Public dependencies like Telerik.Licensing are restored from there.
• Ensure you have a valid Telerik license key when building the project.

Optional: Disable Telerik_v3 Temporarily

If the restore process still attempts to connect to the Telerik online feed:

1. Disable the Telerik_v3 package source temporarily in the Package Sources settings.
2. Restore the project again.

See Also

• Set Up a Local Folder as a NuGet Package Source