Failed to restore project when there is external nuget source configured

I have few configured in nuget.config nuget sources on my machine.

One of them (externalSource) look at external protected source (all the below generated by VS):

<?xml version="1.0" encoding="utf-8"?><configuration><packageSources><add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" /><add key="externalSource" value="https://.external_source./nuget/v3/index.json" /><add key="Microsoft Visual Studio Offline Packages" value="C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\" /></packageSources></configuration>

I can retrieve json configuration from all the sources on my machine in the browser where I can enter proper credentials (ie work with this without any issues). Also, I can easily work with this nuget source in Nuget Manager UI in VS.

The machine where I'm working on also has access to a different nuget source, but this source is not configured anywhere (in VS or any nuget.config).

Now, I create a simple console application:

PS C:\..> dotnet new console --no-restoreThe template "Console App" was created successfully

note: I intentionally skipped restore to limit the question area only to restore logic, without this option, the new console command will fail, even though the project itself will be created.

Now I want to restore created application:

PS C:\..> dotnet restore  Determining projects to restore...C:\Program Files\dotnet\sdk\8.0.100\NuGet.targets(156,5): error : Unable to load the service index for source "https://.external_source./nuget/v3/index.json". [C:\..\test.csproj]C:\Program Files\dotnet\sdk\8.0.100\NuGet.targets(156,5): error :   Response status code does not indicate success: 401 (Unauthorized). [C:\..\test.csproj]

When I enable, detailed logging verbosity, I see that failing happens in this step:

 1>Target "Restore" in file "C:\Program Files\dotnet\sdk\8.0.100\NuGet.targets" from project "C:\..\test.csproj" (entry point):   Task "RemoveDuplicates"   Done executing task "RemoveDuplicates".   Using "RestoreTask" task from assembly "C:\Program Files\dotnet\sdk\8.0.100\NuGet.Build.Tasks.dll".   Task "RestoreTask"     (in) RestoreGraphItems Count '4'     (in) RestoreDisableParallel 'False'     (in) RestoreNoCache 'False'     (in) RestoreIgnoreFailedSources 'False'     (in) RestoreRecursive 'True'     (in) RestoreForce 'False'     (in) HideWarningsAndErrors 'False'     (in) RestoreForceEvaluate 'False'     (in) RestorePackagesConfig 'False'..   CACHE https://api.nuget.org/v3/vulnerabilities/vulnerability.update.json     1>C:\Program Files\dotnet\sdk\8.0.100\NuGet.targets(156,5): error : Unable to load the service index for source https://.external_source./nuget/v3/index.json. [C:\..\test.csproj]       C:\Program Files\dotnet\sdk\8.0.100\NuGet.targets(156,5): error :   Response status code does not indicate success: 401 (Unauthorized). [C:\..\test.csproj]         Assembly loaded during TaskRun (NuGet.Build.Tasks.RestoreTask): System.Diagnostics.StackTrace, Version=8.0.0.0, Culture=neutral, PublicKeyToken=.. (location: C:\Program Files\dotnet\shared\Microsoft.NETCore.App\8.0.0\System.Diagnostics.StackTrace.dll, MVID: .., AppDomain: [Default])         NuGet.Protocol.Core.Types.FatalProtocolException: Unable to load the service index for source https://.external_source./nuget/v3/index.json.          ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 401 (Unauthorized)...

How can I fix it?

Configuration like:

• in nuget.config:

  <packageSourceCredentials>    <externalSource>      <add key="Username" value="name" />      <add key="ClearTextPassword" value=".." />    </externalSource>  </packageSourceCredentials>

• or options for the dotnet restore command: --interactive or --ignore-failed-sources don't help. I can fix it with option --source=nuget.org, but I have to have externalSource configured since in some other cases restoring should happen from this source