While creating Nuget package through Azure DevOps pipeline and adding the package to the Artifacts, you might get the following or similar errors:

error NU1301: Unable to load the service index for source https://xxxx.dev.azure.com/MyApps/_packaging/MyPackage%40Local/nuget/v3/index.json

This could usually happen when you’re Publishing the package to Nuget in a separate job or Stage from the Build step.

To resolve this, you need to do a nuget package restore before publishing the package to Nuget:

steps:
  - task: DotNetCoreCLI@2
    displayName: Nuget package restore
    inputs:
      command: restore
      projects: '$(workingDirectory)/**/$(projectName)*.csproj'
      feedsToUse: 'config'
      nugetConfigPath: $(workingDirectory)/nuget.config
  - task: DotNetCoreCLI@2
    displayName: Create Nuget Package
    inputs:
        command: pack
        versioningScheme: byBuildNumber
        arguments: '--configuration $(buildConfiguration)'
        packagesToPack: '$(workingDirectory)/**/$(projectName).csproj'
        packDestination: '$(Build.ArtifactStagingDirectory)'
  - task: NuGetAuthenticate@0
    displayName: 'NuGet Authenticate'
  - task: NuGetCommand@2
    displayName: 'NuGet push'
    inputs:
      command: push
      publishVstsFeed: 'MyFramework'
      allowPackageConflicts: true

The variables in the above template can be passed from a Pipeline that is triggered by a change to a branch or run manually.