Telerik Nuget package restore in Azure build pipeline fails - azure

Question

I'm attempting to pull Nuget packages from Telerik's Nuget repository into an Azure build pipeline, however, none of the pipeline configuration attempts I've made seem to work. I either receive an error stating my nuget.config is not formatted correctly or a 401 error when connecting to the repository.
The below configuration section is from my build definition. I've tried using NuGetCommand as well as NuGetRestore:
- task: NuGetToolInstaller#1
inputs:
versionSpec: '5.0.2'
- task: NuGetAuthenticate#1
inputs:
nuGetServiceConnections: 'Telerik_v3'
- task: NuGetCommand#2
inputs:
command: 'restore'
restoreSolution: '**/*.sln'
feedsToUse: 'config'
nugetConfigPath: './XXXXXXX/nuget.config'
#'$(System.DefaultWorkingDirectory)/XXXXXXX/NuGet.config'
externalFeedCredentials: 'Telerik_v3'
# - task: NuGetRestore#1
# inputs:
# solution: '**/*.sln'
# selectOrConfig: 'config'
# nugetConfigPath: './XXXXXXX/nuget.config'
Here is my nuget.config:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<packageSources>
<add key="NuGet" value="https://api.nuget.org/v3/index.json" protocolVersion="3"/>
<add key="Telerik_NuGet" value="https://nuget.telerik.com/v3/index.json" protocolVersion="3" />
</packageSources>
</configuration>
Here is the error I receive:
NuGet.Protocol.Core.Types.FatalProtocolException: Unable to load the service index for source https://nuget.telerik.com/v3/index.json. ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 401 (Unauthorized).
Tweaking the configuration slightly I get this error:
##[error]The nuget command failed with exit code(1) and error(NuGet.Configuration.NuGetConfigurationException: NuGet.Config is not valid XML. Path: 'D:\a\1\Nuget\tempNuGet_966.config'. ---> System.Xml.XmlException: An error occurred while parsing EntityName. Line 10, position 46.
I based my build tasks on the NuGetCommandv2 and NuGetRestore v1 documentation as well as what I found on Telerik's site.

Answer 1

When we want to use private nuget packages like Telerik we need to specify credentials in Nuget.config_
Connection name
Feed URL
Username
Password
NOTE:
In order to add a reference to this NuGet package to your project, firstly need to add Telerik credentials into Visual Studio.
example:
dotnet nuget update source "Telerik" --source "https://nuget.telerik.com/v3/index.json" --configfile "nuget.config" --username '*************' --password '***********' --store-password-in-clear-text
Here I found one reference github by Lance McCarthy