VSTS Build suddenly started failing “Unable to load the service index for source ”

Question

In VSTS Build definition, .Net Core Publish task started failing suddenly with below error.

Unable to load the service index for source https://microsoft.pkgs.visualstudio.com/_packaging/Universal.Store/nuget/v3/index.json. Response status code does not indicate success: 401 (Unauthorized).

The same build agent is working for the above package for the same step. It started failing suddenly from October 1st.

Answer 1

You most likely have an expired Personal Access Token in the .NET Core publish step. Check if that step is using any Service Endpoints and verify that any tokens in those endpoints are not expired.