Why can't my Azure DevOps pipeline load stages?

Question

The yaml below creates a pipeline. The pipeline functions as expected, except when you attempt to view/skip stages via the Portal. At this point, I get the error message Unable to load the pipeline's stages.

When I create a pipeline manually via the Portal, using the same ymlPath as the automatically generated pipeline, I am able to load the pipelines stages.

parameters:
  - name: 'branch'
    type: string
    default: 'main'
  - name: 'folderPath'
    type: string
  - name: 'pipelineName'
    type: string
  - name: 'repositoryName'
    type: string
  - name: 'repositoryType'
    type: string
    default: 'tfsgit'
  - name: 'skipFirstRun'
    type: boolean
    default: true
  - name: 'ymlPath'
    type: string
  - name: 'jobName'
    type: string
    default: 'CreatePipeline'
  - name: 'dependsOn'
    type: object
    default: []
  - name: 'displayName'
    type: string
    default: 'Create a Pipeline'
  
jobs:
  - job: '${{ parameters.jobName }}'
    displayName: '${{ parameters.displayName }}'
    dependsOn: '${{ parameters.dependsOn }}'
    pool:
      vmImage: windows-latest
    steps:       
      - script: echo $(System.AccessToken) | az devops login
        displayName: 'Login to DevOps'

      - task: PowerShell@2
        name: 'CreatePipeline'
        displayName: 'Create a Pipeline'
        inputs:
          targetType: 'inline'
          failOnStderr: true
          script: |
            $pipelineResult = (az pipelines create `
              --name "${{ parameters.pipelineName }}" `
              --repository "${{ parameters.repositoryName }}" `
              --folder-path "${{ parameters.folderPath }}" `
              --repository-type "${{parameters.repositoryType }}" `
              --branch "${{ parameters.branch }}" `
              --skip-first-run "${{ parameters.skipFirstrun }}" `
              --yml-path "${{ parameters.ymlPath}}" `
              --debug `
              | ConvertFrom-Json)

            Write-Host "##vso[task.setvariable variable=pipelineId;isOutput=true;]$($pipelineResult.id)"
        env:
          SYSTEM_ACCESSTOKEN: $(System.AccessToken)

1. I have tried running the az pipeline show CLI command directly but face policy issues due to my organisation blocking it.
2. I have tried comparing both pipelines (settings etc) in the Portal and they both seem exactly the same.

Answer 1

My organization recently saw the same issue: we couldn't load our pipeline stages or resources, despite our YAML syntax being fine. I'm not sure if our solution will suit yours, but we found that an empty "Default agent pool for YAML" setting was causing it (seems like a Microsoft bug). To find this setting do the following:

• Navigate to your pipeline and select "Edit"
• Open the kebab menu in the top right and select "Triggers"
• Open the YAML tab, and verify the "Default agent pool for YAML has a value"

I don't believe the value particularly matters. We specify the pool for all our pipeline jobs, so it never gets used. I hope that helps you as it helped us!