Azure DevOps YAML Pipeline Error: While parsing a block mapping did not find expected key

Question

I just created a pipeline using the YAML file and I am always getting the error "/_Azure-Pipelines/templates/webpart.yml: (Line: 41, Col: 27, Idx: 1058) - (Line: 41, Col: 60, Idx: 1091): While parsing a block mapping, did not find expected key.". I already verified the indentation of my YAML file and that looks fine.

Below is my YAML file.

parameters:
  - name: azureSubscription
    type: string
  - name: cdnStorageAccount
    type: string
  - name: cdnResourceGroupName
    type: string
  - name: cdnEndpointName
    type: string
  - name: cdnProfileName
    type: string
  - name: sourceBranchTrigger
    type: string

stages:
  - stage: build_stage
    displayName: "Build"
    jobs:
      - job: build_job
        steps:
          - task: UseNode@1
            displayName: "Use Node 8.x"
            inputs:
              version: "8.x"

          - task: CmdLine@2
            displayName: "Build"
            inputs:
              script: |
                cd ./Webparts
                npm run build-server

          - task: PublishBuildArtifacts@1
            displayName: "Publish Build Artifact (Apps)"
            condition: ne(variables['Build.Reason'], 'PullRequest')
            inputs:
              PathtoPublish: "Webparts/sharepoint/solution/webpart.sppkg
              ArtifactName: Apps

          - task: PublishBuildArtifacts@1
            displayName: "Publish Build Artifact (Scripts)"
            condition: ne(variables['Build.Reason'], 'PullRequest')
            inputs:
              PathtoPublish: "Webparts/temp/deploy"
              ArtifactName: Scripts

Answer 1

In case someone stumbles here, I used pip install yamllint (Thanks for the recommendation @Sibeesh ! ( redhat site ) )

And in my particular case While parsing a block mapping, did not find expected key was caused by bad indentation like ,

stages:
  - stage: repo_deploy_poc
    jobs:
      - job: blah
        steps:
          - bash: |
              echo "hello"

#             echo "hmm"
#             echo "nevermind"
              echo "ok bye"

And looks like it did not like my # not aligned with indentation so changed it to

stages:
  - stage: repo_deploy_poc
    jobs:
      - job: blah
        steps:
          - bash: |
              echo "hello"

              # echo "hmm"
              # echo "nevermind"
              echo "ok bye"

And was fine.

Answer 2

It was due to a missing quotation mark in the task PublishBuildArtifacts@1 for the PathtoPublish. I found this error by using a YAML extension provided by RedHat.

Once you enabled that extension and set the formatted for YAML (SHIFT + ALT + F), it should show you the errors in your YAML file.